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Managing Linux and Virtual Machines?
deijmaster asks: "For a couple of months we have been hearing (as a major consulting firm) IBM people pushing the possibility of installing a Z/Linux VM setup at one of our biggest clients (financial). To a Linux user such as myself this sounds great, at first. Now, I am a bit reluctant when it comes to managing this kind of infrastructure, with little or no local expertise at IBM. Has anyone gone through a Z/Linux VM corporate installation and lived through the management of such a solution?"
That's really not what he means. This is using a completely non unix oriented system (a mainframe) running a VM (which is not an emulator, virtualization is built into mainframes) to run many instances of linux (which isn't emulated either, linux runs natively on mainframes).
Oh, and the Marist linux-390 listserver is well worth subscribing to.
1. What exactly demands this solution?
2. Can a pure Linux box, with mild tweaking, still not be more useful and create less overhead than this?
Someone in this thread mentioned IBM implementing wildly complex systems in order to push consultation, and on some levels it's true. PeopleSoft does it also. In some cases, Oracle will have a go at this tactic. My advice is to do some searching first, without the input of IBM, and see if you can't find a better solution to whatever problem you're trying to remedy.
Well I used to work at similar financial company where IBM was pushing something similar as well. What it boiled down to was the following issues.
1. for the equivalent # of VM's it was more cost effective to buy new Intel hardware. The annual maintaince cost for the IBM more than paid for all new hardware.
2. Software availability. The only thing you could run it would be home grown apps or existing opensource apps. No commercial software was available. This company was an all Oracle shop, no DB2. They're primary opensystems backup solution was Netbackup. Which at the time had no client for linux on Z. (a year ago).
3. In house expertise. They had no linux expertise and very little Unix (solaris & HP) (jr admins at best) expertise. Let alone running linux on a Z.
So to sum it up. It's a very expensive, somewhat propritary and inflexiable environment. If you have a specialized use for it and can justify the cost go for it. Otherwise stick with commodity Intel/AMD hardware. It'll be cheaper and easier in the long run.
I work for a big financial firm in NYC that is using Z/Linux pretty heavily. I have to say that while we are very happy with the results, it is VERY important to have VM people on staff who are also Linux savvy. IBM has been great in getting us set up, but they don't live with the systems. We do. You'll need to be very careful about what you're using the Linux instances for, and take alook at how they'll use hardware resources, like the OSA cards.
With careful planning, and the expectation that it will be a bumpy start, you'' find that it's a very rewarding experience, both personally and professionally.
I wouldn't get hung up on the whole "local" thing. You just have to understand how IBM works. There's no concept of "local" at IBM. At any one point in time, 50% of IBM employees aren't in a traditional work place.
If you have problems, contact IBM and they will get their best people on it. IBM is all about customer service. You never get fired for buying IBM. From an engineers perspective, it's a pita. The best people in a department end up spending most of their time working on customer problems.
Hell, IBM still supports OS/2. If a Z-Series seems to solve your problem, go for it. IBM will take care of you.
http://www.linuxcare.com/
Chrisd
Co-Editor, Open Sources
Open Source Program Manager, Google, Inc.
Actually VM itself is fairly straight forward to administer
The biggest hurdle will be:
This is also where security comes in. Each SVM is really isolated from each other.
One thing to remember too is that VM was (and still is) used by many Universities and colleges -- not as much as it was back in the 70's and 80's, but it still has a presence.
Anyway... just some comments from an old timer VM sysprog
Familiarity with Linux will not help you setting up the zLinux environment. It works like this: You dedicate a few processors of your mainframe to Linux. These processors will run VM, which has:
The users are defined in a "user directory". There, you can specify how much memory, disk and CPU share you want to give to each user. These users, remember, are in fact virtual machines that will boot an image of Linux compiled for the zSeries processor architecture.
If you want to create and take down Linux images frequenlty, you'll have to install and customize some VM scripts that will do the job for you. When the scripts are installed, you can setup a new Linux image (complete with its own disks, IP address, etc.) with a single operator command.
Most sysadmins of a zLinux machine spend a lot of time in VM. So learning VM is essential if you are going to do this job. VM was created 30 years ago and is somewhat primitive in places, but the resource virtualization mechanism is incredibly powerful and makes up for it.
Finally, make sure that people understand that there might be dozens of virtual CPUs defined under VM but only a few real CPUs. If you have 4 CPUs, a Linux user with an absolute CPU share of 25% will have the equivalent of one CPU. If the Linux image is used for recompiling its kernel, it might be a tad slow. The mainframe has great I/O performance but only run-of-the-mill raw CPU speed.
Good luck.
Amdahl's version of Unix was and is UTS. It was spun off in May 2000 as UTS Global LLC. Check out our webpage at http://www.utsglobal.com.
Grain of salt, yada yada...
d bo okAbstracts/sg246824.html?Open
:(
I second the idea that it is very important to have VM skills on site for a customer looking at this. Presumably the customer is already a z/Series account, so they probably already know a thing or two, but they may have bought into the "VM is going away" speech and gotten rid of their VM stuff years ago and gone to z/OS.
Even if they have VM skills from 5-7 years ago - that will still do. VM hasn't changed all that much, it just has some more bells and whistles. So one or two refresher courses for whoever is still around in their shop will get them up to speed on z/VM 4.4 if they knew it 'Back in the day'.
And yes - Linux on VM is still young. Most shops appear to do a lot of 'roll your own' solutions to the administrative problems. Get hooked into the Marist linux390 mailing list, there are a lot of smart folks there who have at least thought about any problem youre likely to have.
I've run/tested every one of SLES 7, 8, RedHat 7.1, 7.2, RHEL3 beta, TurboLinux (old and crusty now) and Debian with pretty much any IBM middleware you could think of. From the linux side - it doesn't know anything about VM, or care. So you as the administrator must make sure it plays politely with the others it lives with. You probably should not just throw 2 Gigabytes of storage at it just because Websphere says it needs it. Running Linux with VM does require some understanding of how to make the most of shared resources. Check out this redbook:
http://publib-b.boulder.ibm.com/Redbooks.nsf/Re
It makes a lot of these points better than I can.
--Anonymous Coward cause I forgot my password
I've done plenty of these. I'm sure a little Googling will reveal who I work for and that I'm probably not lying. I'm also not an IBMer.
As with anything, "it depends." In my experience, L/390 under z/VM works best in I/O-intensive heavy-throughput roles. Do not throw CPU-intensive work at it. If you need CPU, either build an Intel farm, or use an architecture that's designed for serious computing, like a pSeries.
From a manageability standpoint, you will be flabbergasted how much easier it is to manage a z/VM box with 100 Linux instances on it than it is to maintain 100 rackmounted x86 boxes. And once you get your legs under you with VM, it's amazing how tunable the system parameters are. FCON/ESA (now Performance Toolkit, in z/VM 4.4) is really, really your friend in terms of determining where the system hotspots are. And once you've tasted how to deploy additional servers in two minutes without leaving your chair, it's really hard to go back to old-skool provisioning.
Adam
There's another option, too:
Bytemark Hosting offers Linux virtual machines via User-mode Linux.
Bytemark supports Open Source with contributions to Debian and discounts for Open Source developers.
Debian is one of the distro options. Primary DNS on Bytemark's DNS servers is included (running djbdns, win win).
Not quite, though the effect is similar. Both VM and Linux are supported by a combination of software and microcode. However, IBM has been very successful in putting almost all performance critical code sections in microcode. Thus, VM and Linux are 'emulated', but the overall performance usually ends up being quite close to what could be achieved if the support was indeed natively supported.
I presently consult for a company that makes extensive use of a mainframe (s/390 series 5). Yes, these things are rock fucking solid - you've never seen uptime like this with heavy use Unix servers. However, this company still manages to hang the machine once a year in some way or another. They go down, just not as often as any other kind of machine.
Covener, you're right. zSeries suck as number crunchers. They are great at intensive I/O jobs. They are great at consolidating servers that aren't all busy at the same time. But "brute-force an RSA key" is exactly what you don't want to spend your expensive MIPS for.
BTW, I found that on a web server mettle test, large file transfer performance was better on zSeries than on RISC boxes. The larger the files, the more advantage to the mainframe. This is an interesting side-effect of having processors dedicated to I/O and freaking huge I/O bandwidth.
--
Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
Actually not quite true (that the VM person won't understand or like linux).
Linux has actually given VM a shot in the arm. VMers are well aware of that fact. I support a couple of VM systems during the day and play around with Linux at home at night.
Also in terms of culture, I think you would be very surprised with the VM culture. VM spent many years as the unwanted child, VMers had to rely on each other in order to be heard above the MVS roar.
If you take a look at some of the history of the internet you will find VM sitting there (BITNET was basically a collection of VM systems). The listserv concept was originally from VM (CERN was -- might still be -- a big VM site).
If you want to see some of the history of VM you can start here: http://pucc.princeton.edu/~melinda
Actually, I think there was a recent price reduction. $125K. See IBM pricing updates.
The mainframe has a problem. The people who price the add ons. $10,000/GB. Holy Markup Batman!!!!!!! Triple redundacy but you can divide that number by 10 and still have a large number.
It is kind of hard to put larger workloads onto Linux (and hence need to buy more MIPS... and sell more hardware) when it takes over a $100K just to get there. Alas it is priced for folks already waist high in huge legacy software costs. Probably a Wal-Mart special compared to the z/0S fees. Not sure how they can sell alot more "iron" with these prices though.
However, as outlined in other threads.... Linux/390 is aim at niches where it makes sense.
"Keep the customer satisfied" works for me. They know you can go elsewhere so they try very hard to get you not to need to, nor want to.
My favourite analogy is that of European and American Roulette wheels, US wheels have a double zero and European ones don't. They'll likely both get the same money but the US ones want it quicker. (Of course all analogies are flawed, and this one ignores effectively free food and drink at US casinos...)
He was talking about bringing in talent from IBM's Global Services division, these guys bill out at $225 an hour easy.
Good luck at getting one in your door for under $160 an hour - if you sign a 1 year gig maybe but not for a few weeks.
Glonoinha the MebiByte Slayer
Archaic is relative. When was the last time you saw a VT100? yet there are the escape codes stilled being used to move the cursor around, to set colors, etc.
Yes virtual machines have card readers and card punches much the same way that linux has psuedo ttys.
What is going on under the covers is fairly simple. VM sets up a virtual s/390 (z/Series..) environment for each user. It has z/Series architectured type devices (some may be real, others are virtual). A typical VM userid will have:
Now the virtual reader/punch/printer are simply an interface to the VM spooling system. But that interface has to follow the z/Series architecture rules for access a device -- So.. VM uses the card punch and card reader channel commands as the interface. That means that the rules of the device have to be respected.
Now when one IPL's from the spool, the IPL sequences is going to use card readerchannel commands -- so the kernel has to be blocked as 80 byte records.
To put this in perspective, when you boot Linux from a floppy drive, the kernel has to be blocked in to 512 byte records (which is the underlying block size of floppy disk drives if I remember correctly).