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Virtualization Is Not All Roses
An anonymous reader writes "Vendors and magazines are all over virtualization like a rash, like it is the Saviour for IT-kind. Not always, writes analyst Andi Mann in Computerworld." I've found that when it works, it's really cool, but it does add a layer of complexity that wasn't there before. Then again, having a disk image be a 'machine' is amazingly useful sometimes.
This is the exact same pattern that almost every computing technology follows. First the lemmings all rush to sound smart by touting it's benefits. Soon it is the be all and end all in "everyone's" mind. Then the honeymoon fades and people realise it's a useful tool, and toss it into the chest with all the other useful tools to be used where it makes sense.
One of the most uninformative articles ever to hit Slashdot.
"Oh, so now more apps will be competing for that single HW NIC?" Wow. Computerworld, insightful as ever.
I've found that VMware is incredibly useful for testing network booting (PXE) systems. I rolled my own custom Damn Small Linux for PXE booting on our thin client workstations. VMware was great for testing purposes. Everybody loves DSL too, they can listen to streaming audio and MP3s while they work too, since I included mplayer and Flash in Firefox. NX and FreeNX to connect to our terminal server.
Good story, but I disagree in some areas.
Bandwidth concerns. You can have more than one NIC installed on the server and have it dedicated to each virtual machine.
Downtime: If you need to do maintance on the host that may be a slight issue, but I hardly ever have to anything to the host. Also if the host is dying, you can shut donw the Virtual machine and copy it to another server (or move the drive) and bring it up fairly quickly. You also have cluster capability with virtualization.
Half of writing history is hiding the truth.
It is great for replacing things like DNS servers that are mostly CPU. However, don't try running two busy database machines on the same disk - you can't divide it up nearly as well as CPU or bandwidth use.
Also, make sure to try OpenVZ before you try Xen. If you are virtualizing all Linux machines, then VZ is IMO a better choice.
how about an article that makes some recommendations on how to mitigate the problems they identify with virtualization, or point out some non obvious issues?
philo
But it still is useful. Like terminals hooked up to big mainframes, it may make sense to run multiple virtual machines off a single server, or even have the same OS run for the same user in different spaces on a single machine. We have been heading to this point for a while, and now that we have the power, it makes little sense not to use it.
The next thing I am waiting for are very cheap machines, say $150, with no moving parts, only network drivers, that will link to a remote server.
"She's a scientist and a lesbian. She's not going to let it slide." Orphan Black
The absolute only place it has not been appropriate are locations requiring high amounts of disk IO. It has been a godsend everywhere else. All of our web servers, application servers, support servers, management servers, blah blah blah. It's all virtual now. Approximately 175 servers are now virtual. The rest are huge SQL Server/Oracle systems.
License controls are fine. All the major players support flexible VM licensing. The only people that bark about change control are those who simply don't understand virtual infrastructure and a good sit-down solved that issue. "Compliance" has not been an issue for us at all. As far as politics are concerned -- if they can't keep up with the future, then they should get out of IT.
FYI: We run VMware ESX on HP hardware (DL585 servers) connected to an EMC Clariion SAN.
I'm certified for both VMware ESX 2.5 and VMware VI3. VMware's best practices are to never use a single path, whether it be for NIC or FC HBA (storage). VMware also has Virtual Switches, which not only allows you to team NICs for load balancing and failover, but also use port groups (VLANs). You can then view pretty throughput graphs for either physical NICs or virtual adapters. It's crazy amazing(TM).
.5 seconds compared to an IBM xSeries 3850 which takes 6 minutes). Oh, and there is the whole snapshotting feature, memory and disk, which allows for point in time recovery on any host. Yea... downsides indeed.
As for "putting many workloads on a box and uptime," this writer should really take a look at VMware VI3 and Vmotion. Not only can you migrate a running VM without downtime, you can "enter maintenance mode" on a physical host, and using DRS (distributed resource scheduler) it will automatically migrate the VMs to hosts and achieve a load balance between CPU/Memory. It's crazy amazing(TM).
Lastly, just to toot a bit of the virtualization horn... VMware's HA will automatically restart your VMs on other physical hosts in your HA cluster. It's not unusual for a Win2k3 VM to boot in under 20 seconds (VMware's BIOS posts in about
Virtualization is Sysadmin Utopia. -- cvl, a Virtualization Consultant
From what I have seen and experienced the VM video card is the issue. The virtual machine uses the virtual hardware drivers so the actual hardware is largely irrelevant so long as the host OS can handle it. In a desparate attempt to get FFXI installed on my linux machine I resorted to attempting to use VMware only to find out that VMware does not support any kind of 3d accel stuff (again, virtual hardware vs real hardware).
The only change I can believe in is what I find in my couch cushions.
Why is it all of a sudden whenever someone says "Virtualization" they imply that it must be Vmware/Xen/windows/x86 platform.
It's not like these issues haven't existed on other platforms. Mainframes, mini's (as400), Unix (aix/solaris/hpux), heck we've had it on non-computer platforms (VLANs anyone...).
And yes using partitions/LPARs on those platforms required *GASP* planning, but in the age of "click once to install DB and build website" aka "Instant gratification" we refuse to do any actual work prior to installing, downloading, deploying...
How about a few articles comparing AIX/HPUX/Solaris partitions to x86 solutions...
No, no, no. First of all, in a real enterprise type solution (something this author seems unfamiliar with) the entire environment is redundant. "the" server? You don't run anything on "the" server, you run it on a server and you just move the virtual machine(s) to another server as needed when there is a problem or maintenance is needed. It is actually very easy to deal with hardware failures.. you don't ever have to schedule downtime, you just move the VMs, fix the broken node, and move on. For software maintenance you just snapshot the image, do your updates, and if they don't work out, you're back online in no time.
In a physical server environment, each application runs on a separate box with a dedicated network interface card (NIC), Mann explains. But in a virtual environment, multiple workloads share a single NIC, and possibly one router or switch as well.
Uh... well maybe you would just install more nics? It seems the "expert" quoted in this article has played around with some workstation level product and has no idea how enterprise level solutions actually work.
The only valid point I find in this whole article is the mention of additional training and support costs. These can be significant, but the flexibility and reliability of the virtualized environment is very often well worth the cost.
-Lod
Indeed. If you have a proper ESX configuration: At least two hosts, SAN back-end, multiple NIC's, supported hardware - you'll find that almost none of the points are valid.
Teaming, hot-migrations, resource management, and lots of other great tools make modern x86 virtualization really enterprise caliber.
I think that the people that see it as a toy are people that have never used virtualization in the context of a large environment, being used properly with proper hardware. You can virtualize almost any server if you plan properly for it.
In the end, by going virtual you end up actually removing so much complexity from your systems that you'll never know how you did it before. No longer does each server have it's own drivers, quirks, OpenManage/hardware monitor, etc etc. You can create a new VM from a template in 5 minutes, ready to go. You can clone a server in minutes. You can snapshot the disks (and RAM, in ESX3) and you can migrate them to new hardware without bringing them down. You can create scheduled copies of production servers for your test environment. So much more simple then all-hardware.
I'll admit that you shouldn't use virtual servers for everything (yet) but you will eventually be able to run everything virtual, so it's best to get used to it now.
- It's not the Macs I hate. It's Digg users. -
Examine that quote from the article closely. See anything there that indicates virtualization "doesn't work"? No, nor do I. What they are talking about here has nothing to do with how well virtualization works, what they're complaining about is that a particular tool requires competence to use well in various work environments. Well, no one ever said that virtualization would gift brains to some middle level manager, or teach anyone how to use an office suite, or imbue morals and ethics into those who would steal; virtualization lets you run an operating system in a sandbox, sometimes under another operating system entirely. And it does that perfectly well, or in other words, it works very well indeed. I call FUD.
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