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hi
if you have implemented server virtualizatoin, where you hosts a number of "virtual" servers together.., can i ask your experience on it. Does it really save costs (instead of buying many servers ) ? What other pros and cons for server virtualization?
thanks
I’ve played with VMware Workstation quite a bit in a develop environment testing new SW releases/patches to several different platforms (Linux and Win98 through WinXP). My host system (Dell Latitude D600, 768MB Ram) was adequately equipped but not great enough to run more that two VM’s at one time (I’ve run three and the host system was very, very unhappy). I have not played with the GSX or ESX from VMware nor have I played with the Microsoft Virtual Server, so I cannot provide any feed back about them.
I like the flexibility virtualization provides in that you do not need a boatload of systems to test a variety of OSs and configurations. You can take a snapshot of a VM, deploy a patch or a piece of software to it, and if it goes awry roll back the VM to the snapshot. I’ve done this many times and it’s always worked for me.
I’ve also setup Domains and tested Domain trusts, replication; all the silly things I needed to play with for work, certification testing, etc. and it all worked very well for me.
The only draw back is that you are limited to the hardware it’s installed on. I’d like to see something like hardware virtualization where you can simulate a different video card, network card, etc. That would be cool.
I’m trying to convince the powers that be to get the GSX version of VMware and a decent box to run it on so that I can deploy a virtual test LAN (basically a copy of my prod LAN). So if I ever get that I’ll post a follow up ;-)
In my previous position, we set up two ESX machines and hosted about 20-30 servers on them. This is a good way to consolidate servers and save money on hardware in a larger scale environment. We were able to retire a lot of older server systems and reduce the workload on our system admins.
The cons are that the hosting system must be a very high end system with oodles (lots and lots) of RAM and processor. Our ESX boxes were HP 580s with 12 GB RAM and two procs, upgradeable to four, and they had a fiberchannel connection to a SAN. Not all applications/services are appropriate for VMs. Keep in mind that all the hardware access (HD, SAN, RAM, CPU and NIC) are shared. Services or apps that can't live in that environtment must be placed on their own hardware.
Other issues are that a committment to virtualization is expensive on the front end. ESX ain't cheap, but it is the best solution for hosting. It requires training to understand and use correctly. Your hardware becomes a hyper-critical component, more so than usual, so you must have the best with the best support and warranty you can get. The whole thing will fall apart if you try to cheap it out.
For smaller scale situations, I've set up an AD domain on two virtual servers and one virtual workstation on a Dell Optiplex with P4, 2.6ghz, 1 GB RAM and it was an acceptable test environment for mirroring our production AD and testing policy and other things.
You can also use a virtualized domain like the above as a honeypot.
hiQuote:
Originally posted here by rapier57
In my previous position, we set up two ESX machines and hosted about 20-30 servers on them. This is a good way to consolidate servers and save money on hardware in a larger scale environment. We were able to retire a lot of older server systems and reduce the workload on our system admins.
The cons are that the hosting system must be a very high end system with oodles (lots and lots) of RAM and processor. Our ESX boxes were HP 580s with 12 GB RAM and two procs, upgradeable to four, and they had a fiberchannel connection to a SAN. Not all applications/services are appropriate for VMs. Keep in mind that all the hardware access (HD, SAN, RAM, CPU and NIC) are shared. Services or apps that can't live in that environtment must be placed on their own hardware.
Other issues are that a committment to virtualization is expensive on the front end. ESX ain't cheap, but it is the best solution for hosting. It requires training to understand and use correctly. Your hardware becomes a hyper-critical component, more so than usual, so you must have the best with the best support and warranty you can get. The whole thing will fall apart if you try to cheap it out.
For smaller scale situations, I've set up an AD domain on two virtual servers and one virtual workstation on a Dell Optiplex with P4, 2.6ghz, 1 GB RAM and it was an acceptable test environment for mirroring our production AD and testing policy and other things.
You can also use a virtualized domain like the above as a honeypot.
thanks for your input. Can i ask did you consolidate your production servers ? Servers that are
critical for operations? That is to say you put alot of such critical servers onto one single machine ? I have a concern that what if the hardware malfunctions, then all my critical servers will be down? Or is my concern unfounded...:-)
We've tinkered with the idea of using it for running build machines and so on but we've been told by various sources (including one at VMware) that you can experience wierdness. They do not use it themselves for just that reason.
We do however use it for certain kinds of software testing and it seems to work pretty well, and saves us the work and costs of putting together more physical servers.
I can say that VMWare is strides above Microsoft Virtual PC...
When running VMWare I can have 2-3 virtual machines running on my laptop with a gig of ram.
With MS Virtual PC, I can barely have one...it maxes out the CPU...
I have several Linux virtual servers from a company who uses User-Mode Linux to provide virtual servers.
These are pretty good, everything is just like using a physical box, except you can access the console remotely (very useful).
Performance isn't as snappy as using a real dedicated machine, but it is totally acceptable for running normal web sites off.
Of course the physical memory in the machines is divided between all the VMs. Our boxes have 128M of memory each, which is just about enough for basic stuff (Apache + Mysql + PHP etc).
Managing these boxes is apparently quite complicated, but fortunately I don't have to do it. All we do is manage the virtual servers.
They also have a shared virtual filesystem which contains current OS updates so we can update without using up our network bandwidth quota. This is really good.
Slarty
We were thinking of using virtual servers to continue running certain applications that were not windows 2003 compatiable. It worked out as a good compremise for non-critical systems. One of the problems you face of putting a couple on non-critical applications servers on one virtual server host is that the host server then becomes critical as if it fails you have not one application down but three or four. Which means three or four times as many unhappy users. As Ghostmachine said you need to be committied to paying out for the material at the start. It is not something that you can cut costs on.
It will also depend on the type of application being hosted on your virtual server. We found web apllications and database appplications wroked very well on virtual servers and ther was no real problems running two or three of them toghether as long as the host server was properally dimnsioned for the work load. We did have some problems with servers that were analyzing and treating real time data flows.
Having said that most of our really critical applications are on AS400's and other IBM and Unix systems so the question of hosting them on virtual servers didnt really come up.
I am sure you have already seen these but here are Intel's and VMware's takes on virtual servers
intel virtual server page
VMwares virtual server
Sorry to take so long to get back to this.
Yes, we consolidated a lot of _production_ servers/services into the two ESX boxes. Yes, that puts a lot of eggs in the two baskets. That's why you start with really, really good hardware with top drawer, 4-hour on-site, send the tech, quick-turnaround warranties. We bought HP 580s with the best warranty. With the exception of a couple hicks early on, no problems for almost 18 months ... and still cooking.
The DCs and DNS are still on separate, hard boxes. No virtuals for those services.
Also, with two boxes, there is enough room to move the virtual servers from one to the other while you take the one down for repair, maintenance, updates or whatever. This can be accomplished without disrupting services in any user-noticable way through Virtual Center. Things get a little slow for a while, but it works.
Another thing we did. We set up two physical-virtual clusters. One for Exchange and one for SQL. Each cluster had one physical box (active node) and one virtual machine (passive node). This was cool because you really need the hard systems for Exchange and SQL on the active node. But the passive node only needs to be a virtual system. Failover causes a slowness for a while, but doesn't kill the systems.