Consider the above list of UNIX strengths to be also a list of Windows weaknesses. However, there are some specific issues that need to be called out.
1) A GUI bias. Windows 2000 server products continue to be designed with the desktop in mind. There are too many functions that are either too difficult or impossible to perform using a text-based interface.
Why is this important? There are several reasons:
GUI operations are essentially impossible to script. With largenumbers of servers, it is impractical to use the GUI to carry out installation tasks or regular maintenance tasks.
Text-based operations are more versatile; an administrator can usually do more to a system (good and bad) than is provided by the restricted, planned methods using the GUI.
There is in place at Hotmail an established secure channel into the production system, using a text-based secure shell interface.
Using a GUI amounts to hiding the true system modifications from the system administrators and operators. UNIX operators like the sense of control that comes from their ability to modify system tables and configuration files more directly.
Operating a GUI through a slow network connection can be too slow to be useful. Although this is less important, it can still be a consideration when there is a need to administer or diagnose a system through a dialup connection.
There are, indeed, many non-GUI administrative programs provided in the core Windows 2000 product and in the Resource Kit. The problem is that the collection is somewhat arbitrary, incoherent and inconsistent. Programs seem to have been written to fill an immediate need and there is stylistic inconsistency and poor feature coverage.
2) Complexity. A Windows server out of the box is an elaborate system. Although it performs specific tasks well (such as being a web server) there are many services that have a complex set of dependencies, and it is never clear which ones are necessary and which can be removed to improve the system?s efficiency.
3) Obscurity. Some parameters that control the system?s operation are hidden and difficult to fully assess. The metabase is an obvious example. The problem here is that is makes the administrator nervous; in a single-function system he wants to be able to understand all of the configuration-related choices that the system is making on his behalf.
4) Resource utilization. It?s true that Windows requires a more powerful computer than Linux or FreeBSD. In practice, this is a less important constraint. When you are building a large operation, you will use smaller numbers of relatively powerful systems. The PC systems in use at Hotmail are perfectly capable of running Windows, and the machine?s basic power is the same whether it is run with UNIX or Windows. For most of the time, it is only executing application code and most of the extra elaboration is not apparent.
5) Image size. The team was unable to reduce the size of the image below 900MB; Windows contains many complex relationships between pieces, and the team was not able to determine with safety how much could be left out of the image. Although disk space on each server was not an issue, the time taken to image thousands of servers across the internal network was significant. By comparison, the equivalent FreeBSD image size is a few tens of MB.
6) Reboot as an expectation. Windows operations still involves too many reboots. Sometimes they are unnecessary, but operators reboot a system rather than take the time to debug it. For example, a service may be hung, and rather than take the time to find and fix the problem, it is often more convenient to reboot. By contrast, UNIX administrators are conditioned to quickly identify the failing service and simply restart it; they are helped in this by the greater transparency of UNIX and the small number of interdependencies. Some reboots are demanded by an application installation, and are not strictly necessary.
7) License costs. As we will see when discussing load balancing, the license cost of Windows software is a major consideration when converting from the unencumbered UNIX implementations. Although there were no costs to the Hotmail project, as a Microsoft department, the team did consider the software costs in order to make the conversion a useful model for future customers.
They used Server in preference to Advanced Server (no features of Advanced Server were necessary).
They reluctantly used Services for UNIX and Interix, to get access to features that were not adequately provided in Windows. Future releases of Windows will have the features that would make it unnecessary to add those subsystems and avoid their notional cost.
No business analysis was undertaken to determine whether the benefit of the conversion would outweigh the notional cost of the Windows licenses.
Commonly, although not strictly correctly, the generic term UNIX describes a family of operating systems that are deployed on a variety of systems. Although their internal design may be different, the variants appear to their end-users as the same system, with minor (and annoying) differences in usage. There are two variants in use at Hotmail: FreeBSD, which can be used without license cost and is available in source form, and Solaris, which is bundled with Sun hardware. Linux, which is just another UNIX variant, was not used at Hotmail.
The following sections will examine facts about UNIX (specifically FreeBSD) as they relate to the conversion problem. We also consider Apache as an intrinsic part of the UNIX-based solution, in the same way that IIS is an intrinsic part of Windows 2000 Server.
1) Familiarity. Entrepreneurs in the startup world are generally familiar with one version of UNIX (usually through college education), and training in one easily converts to another. When setting up a new enterprise, it?s easy to work with what you know than to take time investigating the alternatives.
2) Reputation for stability. Both the UNIX kernel, and the design techniques it encourages, are renowned for stability. A system of several thousand servers must run reliably and without intervention to restart failed systems. For Windows 2000, we must first prove the stability in the same environment, and we must then convince the rest of the world.
Apache is also designed for stability and correctness, rather than breadth of features or high performance demands.
3) FreeBSD is free. Although there are collateral costs (it?s not particularly easy to set up) the freedom from license costs is a major consideration, especially for a startup. The free availability of source also means that it can be fairly simple (or it can be very difficult) to make local changes [3].
4) Easy to minimize. The typical UNIX server is taking care of one task, not acting as a desktop and development platform for a user. It is particularly easy to cut down the load on the system so that only the minimum number of services is running. This reduced complexity aids stability and transparency.
5) Transparent. It?s easy to look at a UNIX system and know what is running and why. Although its configuration files may have arcane (and sometimes too-simple) syntax, they are easy to find and change.
6) Preference for text files. Most configuration setups, log files, and so on, are plain text files with reasonably short line lengths. Although this may be marginally detrimental to performance (usually in circumstances where it doesn?t matter) it is a powerful approach because a small, familiar set of tools, adapted to working with short text lines, can be used by the administrators for most of their daily tasks. In particular, favorite tools can be used to analyze all the system?s log files and error reports.
7) Powerful but simple scripting languages and tools. Again, familiarity and consistency among UNIX implementations is the key. Over the years, UNIX versions have evolved a good set of single-function commands and shell scripting languages that work well for ad-hoc and automated administration. The shell scripting languages fall just short of being a programming language (they have less power than VBScript or JScript). This may seem to be a disadvantage, but we must remember that operators are not programmers; having to learn a block-structured programming language is a resistance point. Scripts that combine executables into pipelines are simple to build incrementally and experimentally, and even the experienced Hotmail administrators seem to be taking that approach for special purpose scripts (using CMD) rather than authoring with one of the object-oriented scripts.
On the other hand, PERL (another language that has grown organically with a lot of community feedback) is more of a programming than scripting language. It is popular for repeated, automated tasks that can be developed and optimized by senior administrative staff who do have the higher level of programming expertise required.
We believe Hotmail is instructive as an example of the large Internet server site. It is one of the largest such sites on the planet, so we should be judicious in applying its principles to sites that are comparatively/very/ small, and don?t have the issues deriving from multiplication of resources.
As stated above, we are concentrating on the front-end web servers. Although some of the following comments are also applicable to the database machines, we will not address them specifically in this paper.
1) Restricted, well-controlled application. The application under UNIX was a collection of CGI programs, serving about 100 distinct URLs, which have been converted to an ISAPI module. The programs are written in C++. The entire application is under the control of one team, and its architecture is well understood by all of the teams (dev, test and operations). Updates are only due to scheduled code releases, or hotfixes. This contrasts with a site like microsoft.com, which has many different authors and continuous updates.
2) Lights-out administration. All the servers are in a controlled facility that may be staffed by contractors, and it should not be necessary for skilled staff to visit the individual machines for any reason. Machines should be self-monitoring, and Operations staff should be able to maintain them remotely using minimal interaction.
3) Multiple identically configured machines. This leads to a need to have all regular system administration functions, including OS and application update, be scripted, rapid, reliable, and non-interactive. There is simply not time for an administrator to interact personally with all machines. A load-balancing mechanism routes customer requests from a virtual address to one of the real servers.
4) System costs suffer multiplicative effects. Adding a VGA monitor or a second NIC to a server, or running a serial cable to it, may be pocket change when applied to a single machine. Purchasing several thousand such devices, however, becomes a significant investment and has to be thoroughly justified.
5) 100% availability. A large Internet site must provide service 24x7. Furthermore, the full capacity should be available all the time. Hotmail?s load fluctuates daily according to the time across the US, but not by much; the international usage is high.
6) Simultaneous upgrade. The pervious two points mean that the servers must be upgraded essentially simultaneously, unless some kind of server affinity mechanism can be implemented per user session. Since a typical user interaction involves several clicks, it would not be good for a user to jump backwards and forwards between code releases; the problems would range from inconsistency in style to (apparently) half-implemented new features.
7) No personal machines or accounts. All machines are assumed to be secure because of physical location and electrical isolation. Generally speaking, when an administrator is operating on the server or a scheduled tasks runs, full administrative privileges are given. This increases the danger, but reduces the load required to maintain and synchronize accounts.
8) Remote monitoring. All performance monitoring is done by querying the server or by automated reports, and monitoring uses the single NIC. In Hotmail?s case, there is plenty of spare network headroom on each server for this monitoring not to penalize the primary operation.
9) No architectural limits on growth. An Internet site expects to keep growing, and built-in limits that seem unreasonably high in the early days will one day loom up and need to be fixed, using resources that should be enhancing the site. Hotmail has grown from 9 million accounts when it was acquired by Microsoft, to 100 million in July 2000, without significant changes in the hardware or software architecture.
The final four items are more closely related to Hotmail?s architectural choices, but we believe they are representative of the market.
10) Scale-out. The Hotmail website is built from several modules, with each module present in different multiples and able to be scaled out almost indefinitely. In this phase of the project, we are considering the front-end, the web servers that house all of the user interface logic and some parts of the business logic. Among the servers, the majority (?front doors?) runs some code in response to each click, and these were the primary targets for conversion. The machines are single-board x86 PCs, moderately powerful, using Apache, running on FreeBSD version 3.0, to deliver content. Fortunately, these servers are good Windows 2000 hosts.
There are also some servers that serve static content and will be almost trivial to convert once the front doors have been converted. Administration of these servers will use the same methodology as the front doors. They also run on FreeBSD, using the server ?boa?, which is optimized for serving static content rapidly.
11) Configuration conservatism. There are more than 3,000 front door machines, all identically configured. Having the servers essentially identical is important to the operators? ability to administer the site. The approach to the hardware is very conservative: once a hardware configuration is established, it is easy to keep rolling out copies rather than try to qualify a newer model.
This conservatism also applies to the software design. The need to run the project on Internet Time [1] has an impact on this project in several ways: in this case, designers always need to be improving the application and there is little resource left over for redesigning the basic architecture. Furthermore, the various modules of the site are developed independently, creating a force for stability in the internal protocols.
12) Design for stability. Virtually continuous uptime and a consistent response time are crucial. This is achieved by some overcapacity, and highly reliable load-balancing hardware (Cisco Local Director). Local Director is just another module in the scale-out solution.
13) Controlled and understood systems. A fact about UNIX is that it is easy for an administrator to ensure that there are no irrelevant services running. As well as giving the potential for maximizing performance, it is useful to be sure that there are no random TCP/IP or UDP ports open that could be used as a basis for an attack. To some, this transparency is intrinsic to UNIX, but it also comes from a greater familiarity among system administrators with its internal workings.
The headless nature of the systems, and their remote location, have a profound influence on the way the systems are administered. Headless operation means that any direct interaction will be through a remote session (telnet or Terminal Server); nobody will be able to detect an important dialog on the console [2] , and even a bluescreen is not apparent. Remote operation means that there is a specific cost associated with walking up to the machine. The site is serviced by contractors whose job is mainly limited to replacing failed servers and rebooting on demand; it is possible to attach a monitor and keyboard to a running system, but that is operationally an exception.
Microsoft acquired Hotmail at the end of 1997 as a going concern. The service?s creators had defined a two-layer architecture built around various UNIX systems:
Front end web servers, built with dual Pentium systems on racked motherboards, running Apache on FreeBSD (a configuration with no need to install licensed software)
Back end file stores, built with Sun Enterprise 4500 servers, running Solaris 2.6 (Sun?s UNIX) and with all user data stored on RAID arrays, accessed using very simple filing semantics
Incoming mail listeners, built on Sun Sparc 5 processors, and interacting directly with the back end
Name/password verification engines, build on Enterprise 4500 servers
Member Directory, built on PCs with NT and SQL
The conversion of the Hotmail web servers to Windows is an ongoing project with several rationales. The team was hoping for better utilization of the existing hardware resources. The superior development and internationalization tools are important. A Microsoft property should eat its own dogfood. Finally, we wished to use the conversion experience as a model for other UNIX conversions that we hope to carry out in the future.
The first phase of the conversion, described here, was limited to the web servers. Appropriate hardware was already in place, and the planning and development staff were confident that they already understood how to perform the conversion successfully.
There were several constraints on the conversion process, which are probably typical of the average Internet site:
Hotmail has established an 8-week cycle of version upgrades, and there was a desire (and some partner pressure) to keep that cycle going.
It is essential to keep the service running continuously.
The staff is small, and there was not an opportunity to add staff.
lamenes filter won't let me post the whole document so I will have to break it up
Abstract
This white paper discusses the approach used to convert the Hotmail web server farm from UNIX to Windows 2000, and the reasons the features and techniques were chosen. It will focus primarily on the planners, developers, and system administrators. The purpose of the paper is to provide insight for similar deployments using Windows 2000. We will discuss the techniques from the viewpoint of human engineering as well as software engineering.
Early results from the conversion, which was limited to the front-end web servers, are:
Windows 2000 provides much better throughput than UNIX.
Windows 2000 provides slightly better performance than UNIX.
There is potential, not yet realized, for stability of individual systems to be equal to that of UNIX. The load-balancing technology ensures that the user experience of the service is that stability is as good as it was before the conversion.
As this paper will show, while the core features of Windows 2000 are able to run the service, its administrative model is not well suited to the conversion.
The observations related here are derived from experience gained at a single site. More work would be needed to establish whether they are representative.
Looks like the judge has approved most of the provisions I wonder whether the nine states, which had rejected the settlement will appeal Kollar-Kotelly's decision?
If the Echostar deal falls through, it could clear the way for Rupert Murdoch's News Corporation to bid to buy Hughes from General Motors.
Although News Corp has distanced itself from the concerted lobbying campaign against the merger, it is an open secret in Washington that Mr Murdoch's group has lobbied Capitol Hill and backed consumer associations opposed to the deal.
But isn't that the whole point? if you've got a product you can charge whatever you like after all people don't have to use the service. I think however that they will set an attractive price point well attractive in comparison to the current cost of making calls using air phones which IIRC are $4 to connect and $5 per minute.
Not sure how much this will help Apple. This is one of their biggest markets already and they already lots of special deals already for educators on hardware and software. Maybe they should have gone for colleges as well but I guess the marketing dollars wouldn't stretch that far.
One thing became immediately apparent when making real world comparisons to out-of-the-box web server solutions from Dell, Compaq, Sun and others and that's the fact that we're much faster and able to offer substantially higher output bandwidth than comparable offerings from these OEMs.
What real world comparisons? The software section only mentions Win2k pro but this is patently not a real world comparision. It's designed to run on the desktop and it's been limited it to 10 concurrent TCP/IP connections by MS so that anyone looking to set up a proper server will need to get the Server or Advanced versions
The article goes on to say
With Linux however you can basically turn it on and walk away, provided you got a system administrator that knows what he's doing and has set up everything correctly.
maybe their sysadmin didn't/dosen't know what he was doing!!
So could you please explain using standard evolutionary theory
how an ordinary beetle, through a series of random, accidental mutations, acted upon by natural selection, could gradually change into a bombardier beetle.
Re:that doesn't mean they'll produce good games
on
Microsoft Buys Rare
·
· Score: 1
yeah check out rare's press release on their web site for a confirmation of those figures.
Clean Flicks side. They've bought the video each time and no one is forced to buy the cleaned up version are they? What's the difference between this and with people doing their own editing. They are simply providing a service.
The article's pretty interesting but doesn't really go into too much detail. Does anyone know what Black and White would have been written in and what tools were used?
I think it's because in the past the universe had more matter for the black holes to consume. But eventually once they had consumed all the matter around themselves they became dormant/inactive and thus fairly hard to see.
Why does it need to be said? Why would msnbc agree to become a mouthpiece for MS and write blatantly untrue articles. They would soon lose credibility and end up in court.
Slashdot Mirror
Consider the above list of UNIX strengths to be also a list of Windows
weaknesses. However, there are some specific issues that need to be
called out.
1) A GUI bias. Windows 2000 server products continue to be designed with the desktop in mind. There are too many functions that are either
too difficult or impossible to perform using a text-based interface.
Why is this important? There are several reasons:
GUI operations are essentially impossible to script. With largenumbers of servers, it is impractical to use the GUI to carry out
installation tasks or regular maintenance tasks.
Text-based operations are more versatile; an administrator can usually do more to a system (good and bad) than is provided by the restricted, planned methods using the GUI.
There is in place at Hotmail an established secure channel into the production system, using a text-based secure shell interface.
Using a GUI amounts to hiding the true system modifications from the system administrators and operators. UNIX operators like the sense of control that comes from their ability to modify system tables and configuration files more directly.
Operating a GUI through a slow network connection can be too slow to be useful. Although this is less important, it can still be a
consideration when there is a need to administer or diagnose a system through a dialup connection.
There are, indeed, many non-GUI administrative programs provided in the core Windows 2000 product and in the Resource Kit. The problem is that
the collection is somewhat arbitrary, incoherent and inconsistent. Programs seem to have been written to fill an immediate need and there
is stylistic inconsistency and poor feature coverage.
2) Complexity. A Windows server out of the box is an elaborate system. Although it performs specific tasks well (such as being a web
server) there are many services that have a complex set of dependencies, and it is never clear which ones are necessary and which can be removed
to improve the system?s efficiency.
3) Obscurity. Some parameters that control the system?s operation are hidden and difficult to fully assess. The metabase is an obvious
example. The problem here is that is makes the administrator nervous; in a single-function system he wants to be able to understand all of the
configuration-related choices that the system is making on his behalf.
4) Resource utilization. It?s true that Windows requires a more powerful computer than Linux or FreeBSD. In practice, this is a less
important constraint. When you are building a large operation, you will use smaller numbers of relatively powerful systems. The PC systems in
use at Hotmail are perfectly capable of running Windows, and the machine?s basic power is the same whether it is run with UNIX or Windows. For most of the time, it is only executing application code and most of the extra elaboration is not apparent.
5) Image size. The team was unable to reduce the size of the image below 900MB; Windows contains many complex relationships between pieces, and the team was not able to determine with safety how much could be left out of the image. Although disk space on each server was not an issue, the time taken to image thousands of servers across the internal network was significant. By comparison, the equivalent FreeBSD image size is a few tens of MB.
6) Reboot as an expectation. Windows operations still involves too many reboots. Sometimes they are unnecessary, but operators reboot a system rather than take the time to debug it. For example, a service may be hung, and rather than take the time to find and fix the problem, it
is often more convenient to reboot. By contrast, UNIX administrators are conditioned to quickly identify the failing service and simply restart
it; they are helped in this by the greater transparency of UNIX and the small number of interdependencies. Some reboots are demanded by an
application installation, and are not strictly necessary.
7) License costs. As we will see when discussing load balancing, the license cost of Windows software is a major consideration when
converting from the unencumbered UNIX implementations. Although there were no costs to the Hotmail project, as a Microsoft department, the team did consider the software costs in order to make the conversion a useful model for future customers.
They used Server in preference to Advanced Server (no features of Advanced Server were necessary).
They reluctantly used Services for UNIX and Interix, to get access to features that were not adequately provided in Windows. Future
releases of Windows will have the features that would make it unnecessary to add those subsystems and avoid their notional cost.
No business analysis was undertaken to determine whether the benefit of the conversion would outweigh the notional cost of the
Windows licenses.
Advantages of UNIX
.
Commonly, although not strictly correctly, the generic term UNIX
describes a family of operating systems that are deployed on a variety
of systems. Although their internal design may be different, the
variants appear to their end-users as the same system, with minor (and
annoying) differences in usage. There are two variants in use at
Hotmail: FreeBSD, which can be used without license cost and is
available in source form, and Solaris, which is bundled with Sun
hardware. Linux, which is just another UNIX variant, was not used at
Hotmail.
The following sections will examine facts about UNIX (specifically
FreeBSD) as they relate to the conversion problem. We also consider
Apache as an intrinsic part of the UNIX-based solution, in the same way
that IIS is an intrinsic part of Windows 2000 Server.
1) Familiarity. Entrepreneurs in the startup world are generally
familiar with one version of UNIX (usually through college education),
and training in one easily converts to another. When setting up a new
enterprise, it?s easy to work with what you know than to take time
investigating the alternatives.
2) Reputation for stability. Both the UNIX kernel, and the design
techniques it encourages, are renowned for stability. A system of
several thousand servers must run reliably and without intervention to
restart failed systems. For Windows 2000, we must first prove the
stability in the same environment, and we must then convince the rest of
the world.
Apache is also designed for stability and correctness, rather than
breadth of features or high performance demands.
3) FreeBSD is free. Although there are collateral costs (it?s not
particularly easy to set up) the freedom from license costs is a major
consideration, especially for a startup. The free availability of source
also means that it can be fairly simple (or it can be very difficult) to
make local changes [3]
4) Easy to minimize. The typical UNIX server is taking care of one
task, not acting as a desktop and development platform for a user. It is
particularly easy to cut down the load on the system so that only the
minimum number of services is running. This reduced complexity aids
stability and transparency.
5) Transparent. It?s easy to look at a UNIX system and know what is
running and why. Although its configuration files may have arcane (and
sometimes too-simple) syntax, they are easy to find and change.
6) Preference for text files. Most configuration setups, log files,
and so on, are plain text files with reasonably short line lengths.
Although this may be marginally detrimental to performance (usually in
circumstances where it doesn?t matter) it is a powerful approach because
a small, familiar set of tools, adapted to working with short text
lines, can be used by the administrators for most of their daily tasks.
In particular, favorite tools can be used to analyze all the system?s
log files and error reports.
7) Powerful but simple scripting languages and tools. Again,
familiarity and consistency among UNIX implementations is the key. Over
the years, UNIX versions have evolved a good set of single-function
commands and shell scripting languages that work well for ad-hoc and
automated administration. The shell scripting languages fall just short
of being a programming language (they have less power than VBScript or
JScript). This may seem to be a disadvantage, but we must remember that
operators are not programmers; having to learn a block-structured
programming language is a resistance point. Scripts that combine
executables into pipelines are simple to build incrementally and
experimentally, and even the experienced Hotmail administrators seem to
be taking that approach for special purpose scripts (using CMD) rather
than authoring with one of the object-oriented scripts.
On the other hand, PERL (another language that has grown organically
with a lot of community feedback) is more of a programming than
scripting language. It is popular for repeated, automated tasks that can
be developed and optimized by senior administrative staff who do have
the higher level of programming expertise required.
Critical Features of Hotmail as a .COM Site
/very/ small, and don?t have the issues deriving from
We believe Hotmail is instructive as an example of the large Internet
server site. It is one of the largest such sites on the planet, so we
should be judicious in applying its principles to sites that are
comparatively
multiplication of resources.
As stated above, we are concentrating on the front-end web servers.
Although some of the following comments are also applicable to the
database machines, we will not address them specifically in this paper.
1) Restricted, well-controlled application. The application under
UNIX was a collection of CGI programs, serving about 100 distinct URLs,
which have been converted to an ISAPI module. The programs are written
in C++. The entire application is under the control of one team, and its
architecture is well understood by all of the teams (dev, test and
operations). Updates are only due to scheduled code releases, or
hotfixes. This contrasts with a site like microsoft.com, which has many
different authors and continuous updates.
2) Lights-out administration. All the servers are in a controlled
facility that may be staffed by contractors, and it should not be
necessary for skilled staff to visit the individual machines for any
reason. Machines should be self-monitoring, and Operations staff should
be able to maintain them remotely using minimal interaction.
3) Multiple identically configured machines. This leads to a need
to have all regular system administration functions, including OS and
application update, be scripted, rapid, reliable, and non-interactive.
There is simply not time for an administrator to interact personally
with all machines. A load-balancing mechanism routes customer requests
from a virtual address to one of the real servers.
4) System costs suffer multiplicative effects. Adding a VGA monitor
or a second NIC to a server, or running a serial cable to it, may be
pocket change when applied to a single machine. Purchasing several
thousand such devices, however, becomes a significant investment and has
to be thoroughly justified.
5) 100% availability. A large Internet site must provide service
24x7. Furthermore, the full capacity should be available all the time.
Hotmail?s load fluctuates daily according to the time across the US, but
not by much; the international usage is high.
6) Simultaneous upgrade. The pervious two points mean that the
servers must be upgraded essentially simultaneously, unless some kind of
server affinity mechanism can be implemented per user session. Since a
typical user interaction involves several clicks, it would not be good
for a user to jump backwards and forwards between code releases; the
problems would range from inconsistency in style to (apparently)
half-implemented new features.
7) No personal machines or accounts. All machines are assumed to be
secure because of physical location and electrical isolation. Generally
speaking, when an administrator is operating on the server or a
scheduled tasks runs, full administrative privileges are given. This
increases the danger, but reduces the load required to maintain and
synchronize accounts.
8) Remote monitoring. All performance monitoring is done by
querying the server or by automated reports, and monitoring uses the
single NIC. In Hotmail?s case, there is plenty of spare network headroom
on each server for this monitoring not to penalize the primary operation.
9) No architectural limits on growth. An Internet site expects to
keep growing, and built-in limits that seem unreasonably high in the
early days will one day loom up and need to be fixed, using resources
that should be enhancing the site. Hotmail has grown from 9 million
accounts when it was acquired by Microsoft, to 100 million in July 2000,
without significant changes in the hardware or software architecture.
The final four items are more closely related to Hotmail?s architectural
choices, but we believe they are representative of the market.
10) Scale-out. The Hotmail website is built from several modules, with
each module present in different multiples and able to be scaled out
almost indefinitely. In this phase of the project, we are considering
the front-end, the web servers that house all of the user interface
logic and some parts of the business logic. Among the servers, the
majority (?front doors?) runs some code in response to each click, and
these were the primary targets for conversion. The machines are
single-board x86 PCs, moderately powerful, using Apache, running on
FreeBSD version 3.0, to deliver content. Fortunately, these servers are
good Windows 2000 hosts.
There are also some servers that serve static content and will be almost
trivial to convert once the front doors have been converted.
Administration of these servers will use the same methodology as the
front doors. They also run on FreeBSD, using the server ?boa?, which is
optimized for serving static content rapidly.
11) Configuration conservatism. There are more than 3,000 front door
machines, all identically configured. Having the servers essentially
identical is important to the operators? ability to administer the site.
The approach to the hardware is very conservative: once a hardware
configuration is established, it is easy to keep rolling out copies
rather than try to qualify a newer model.
This conservatism also applies to the software design. The need to run
the project on Internet Time [1] has an impact on this project
in several ways: in this case, designers always need to be improving the
application and there is little resource left over for redesigning the
basic architecture. Furthermore, the various modules of the site are
developed independently, creating a force for stability in the internal
protocols.
12) Design for stability. Virtually continuous uptime and a consistent
response time are crucial. This is achieved by some overcapacity, and
highly reliable load-balancing hardware (Cisco Local Director). Local
Director is just another module in the scale-out solution.
13) Controlled and understood systems. A fact about UNIX is that it is
easy for an administrator to ensure that there are no irrelevant
services running. As well as giving the potential for maximizing
performance, it is useful to be sure that there are no random TCP/IP or
UDP ports open that could be used as a basis for an attack. To some,
this transparency is intrinsic to UNIX, but it also comes from a greater
familiarity among system administrators with its internal workings.
The headless nature of the systems, and their remote location, have a
profound influence on the way the systems are administered. Headless
operation means that any direct interaction will be through a remote
session (telnet or Terminal Server); nobody will be able to detect an
important dialog on the console [2] , and even a bluescreen is
not apparent. Remote operation means that there is a specific cost
associated with walking up to the machine. The site is serviced by
contractors whose job is mainly limited to replacing failed servers and
rebooting on demand; it is possible to attach a monitor and keyboard to
a running system, but that is operationally an exception.
Microsoft acquired Hotmail at the end of 1997 as a going concern. The
service?s creators had defined a two-layer architecture built around
various UNIX systems:
Front end web servers, built with dual Pentium systems on
racked motherboards, running Apache on FreeBSD (a configuration with no
need to install licensed software)
Back end file stores, built with Sun Enterprise 4500 servers,
running Solaris 2.6 (Sun?s UNIX) and with all user data stored on RAID
arrays, accessed using very simple filing semantics
Incoming mail listeners, built on Sun Sparc 5 processors, and
interacting directly with the back end
Name/password verification engines, build on Enterprise 4500
servers
Member Directory, built on PCs with NT and SQL
The conversion of the Hotmail web servers to Windows is an ongoing
project with several rationales. The team was hoping for better
utilization of the existing hardware resources. The superior development
and internationalization tools are important. A Microsoft property
should eat its own dogfood. Finally, we wished to use the conversion
experience as a model for other UNIX conversions that we hope to carry
out in the future.
The first phase of the conversion, described here, was limited to the
web servers. Appropriate hardware was already in place, and the planning
and development staff were confident that they already understood how to
perform the conversion successfully.
There were several constraints on the conversion process, which are
probably typical of the average Internet site:
Hotmail has established an 8-week cycle of version upgrades,
and there was a desire (and some partner pressure) to keep that cycle going.
It is essential to keep the service running continuously.
The staff is small, and there was not an opportunity to add staff.
lamenes filter won't let me post the whole document so I will have to break it up
Abstract
This white paper discusses the approach used to convert the Hotmail web
server farm from UNIX to Windows 2000, and the reasons the features and
techniques were chosen. It will focus primarily on the planners,
developers, and system administrators. The purpose of the paper is to
provide insight for similar deployments using Windows 2000. We will
discuss the techniques from the viewpoint of human engineering as well
as software engineering.
Early results from the conversion, which was limited to the front-end
web servers, are:
Windows 2000 provides much better throughput than UNIX.
Windows 2000 provides slightly better performance than UNIX.
There is potential, not yet realized, for stability of
individual systems to be equal to that of UNIX. The load-balancing
technology ensures that the user experience of the service is that
stability is as good as it was before the conversion.
As this paper will show, while the core features of Windows
2000 are able to run the service, its administrative model is not well
suited to the conversion.
The observations related here are derived from experience gained at a
single site. More work would be needed to establish whether they are
representative.
Don't be silly everyone knows it was Al Gore.
Looks like the judge has approved most of the provisions I wonder whether the nine states, which had rejected the settlement will appeal Kollar-Kotelly's decision?
Although News Corp has distanced itself from the concerted lobbying campaign against the merger, it is an open secret in Washington that Mr Murdoch's group has lobbied Capitol Hill and backed consumer associations opposed to the deal.
But isn't that the whole point? if you've got a product you can charge whatever you like after all people don't have to use the service. I think however that they will set an attractive price point well attractive in comparison to the current cost of making calls using air phones which IIRC are $4 to connect and $5 per minute.
Not sure how much this will help Apple. This is one of their biggest markets already and they already lots of special deals already for educators on hardware and software. Maybe they should have gone for colleges as well but I guess the marketing dollars wouldn't stretch that far.
What real world comparisons? The software section only mentions Win2k pro but this is patently not a real world comparision. It's designed to run on the desktop and it's been limited it to 10 concurrent TCP/IP connections by MS so that anyone looking to set up a proper server will need to get the Server or Advanced versions
The article goes on to say
With Linux however you can basically turn it on and walk away, provided you got a system administrator that knows what he's doing and has set up everything correctly.
maybe their sysadmin didn't/dosen't know what he was doing!!
IIRC the crash of that American Airlines plane in New York on Nov 12 also brought a few sites to a near-standstill.
Lol, missed the link somehow, doh! thanks for pointing that out Latent. I think i need to evolve my reading skills a bit more.
So could you please explain using standard evolutionary theory
how an ordinary beetle, through a series of random, accidental mutations, acted upon by natural selection, could gradually change into a bombardier beetle.
yeah check out rare's press release on their web site for a confirmation of those figures.
Clean Flicks side. They've bought the video each time and no one is forced to buy the cleaned up version are they? What's the difference between this and with people doing their own editing. They are simply providing a service.
Check out
www.pirate-radio.co.uk
Nice radio station play all kinds house, DnB & Jungle old skool, Tekno etc etc. Have look at the schedule for Djs and music styles.
Job0
The article's pretty interesting but doesn't really go into too much detail. Does anyone know what Black and White would have been written in and what tools were used?
The URL for the Economist article is http://www.economist.com/displayStory.cfm?Story_ID =539674
Does anyone know why a lot of these pre-humans been found in Kenya and by members the Leakey family?
'They sight "current market conditions"' shouldn't that be cite??
I think it's because in the past the universe had more matter for the black holes to consume. But eventually once they had consumed all the matter around themselves they became dormant/inactive and thus fairly hard to see.
What re u getting at? Being able to encrpyt stuff on your pc dosen't mean that your privacy is protected does it?
Why does it need to be said? Why would msnbc agree to become a mouthpiece for MS and write blatantly untrue articles. They would soon lose credibility and end up in court.
what? like yours?