Hello,
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems. So I thought I would ask here what experience people have had with this and what issues that you all think should be considered?
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
Anyway thank you for your time and any experiences / knowledge you are willing to share :)
Quoting Clint Dilks clintd@scms.waikato.ac.nz:
Hello,
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems. So I thought I would ask here what experience people have had with this and what issues that you all think should be considered?
Xen is great - however you will need Full virtualisation support in your hardware. These are shown as the ?vmx? flag for Intel or ?svm? for AMD CPUs in /proc/cpuinfo.
If you are running Windows guest in a linux Xen domain, you will want to pay for the Xen licenses. This gives you access to the windows drivers for disk and network etc - which improves performance immensely.
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
I can only really speak for Xen...
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
I'd say VMWare would be the way to do this - if you really had to.
Anyway thank you for your time and any experiences / knowledge you are willing to share :)
The learning curve for Xen is huge. I would suggest a few things though if you decide to use it.
1) Setup your Dom0 (the host) disk to use LVM. You will want to make MANY partitions. Use a raw disk partition for disk access instead of a file as the disk - performance is much better this way.
2) If you're going to add Windows as a guest OS, make sure you get the Windows drivers. This is something you have to pay for, but the performance increase will be well worth it.
3) use 'xm top' on Dom0 to monitor what your guest systems are doing. Get yourself a multi processor system, and divide up usage between physical CPUs. This way, you get the best usage of your hardware.
4) Get lots and lots of RAM. We use systems with 8Gb RAM. We give the hypervisor 256Mb, and then chunks of 256Mb, 512Mb or 1Gb to each DomU depending on usage.
On Tue, 2007-09-18 at 11:20 +1200, Clint Dilks wrote:
Hello,
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems. So I thought I would ask here what experience people have had with this and what issues that you all think should be considered?
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
Anyway thank you for your time and any experiences / knowledge you are willing to share :)
I use Xen personally and at work I work with VMware. I don't have any machines personally that have hardware virtualization extensions in the processor, so I'm only doing para-virtualization with CentOS 5 as host and guests. Documentation seems a little sparse if you want to deviate from the default configuration too much in Xen. Other than that I've been very happy with Xen.
At work we've been playing with VMware Infrastructure 3. If you are going to go the VMware route, this is by far the best bang for your buck. You are able to manage several VM hosts under one interface, and if you are running Windows as a guest you can do some pretty neat things (coming soon for the Linux side). I've also used the free version, VMware Server (also called GSX, Infrastructure comes with the version called ESX) on both Windows and Linux...prefer using Linux though as the host (much better stability and low-level options if you are into customizing the environment).
Any more questions, like specifics, please ask. I've been using Xen and VMware for several months now.
On Tue, 2007-09-18 at 11:20 +1200, Clint Dilks wrote:
Hello,
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems. So I thought I would ask here what experience people have had with this and what issues that you all think should be considered?
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
Those are probably the top contenders.
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
No. If there are reasons, they are beyond my understanding. :-)
Anyway thank you for your time and any experiences / knowledge you are willing to share :)
I use VMware Server & Workstation - primarily for testing new Linux releases and for running Windows apps under Linux. Have run some services for testing purposes and find performance and functionality to be pretty good.
You may want to join the new CentOS Virtualization list to find a more targeted audience:
http://lists.centos.org/mailman/listinfo/centos-virt
Phil
Clint Dilks wrote:
Hello,
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems. So I thought I would ask here what experience people have had with this and what issues that you all think should be considered?
Irrespective of which virtual server solution you choose be aware that virtualization brings with it steep storage requirements. Think of providing around 1TB of RAID10 storage for 20 guests. VMs do lots of tiny random IOs so for 20 guests split between 2 servers I provide 500GB of RAID10 to each via iSCSI SAN.
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
Not really.
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
I do at work so I can prototype some Linux stuff on my Windows box.
Anyway thank you for your time and any experiences / knowledge you are willing to share :)
I would try both VMware server and Xen on CentOS, if you have 2 servers set them up side by side and plugged into your storage SAN. Run them through their paces, do some benchmarks get a feel for ease of use and maintenance.
When your ready and have a budget you can move up to the commercial versions, ESX and Xen Enterprise.
-Ross
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Dear,
Yes, VMware is the product which is basically in the market. I have installed and use once i mean about 2 years back.
Well, through my research, VMware is only good if your are in a "Tesing Environment". It is not recommended in the production environment. Because of following reasons,
It uses Kernel Resources upto high and u need very High End Server IF u are using 3 etc applications like (DNS, WEB, FTP), if the machine goes down all your three application goes down High Demanding of memory
Regards,
Umair Shakil ETD
On 9/18/07, Ross S. W. Walker rwalker@medallion.com wrote:
Clint Dilks wrote:
Hello,
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems. So I thought I would ask here what experience people have had with this and what issues that you all think should be considered?
Irrespective of which virtual server solution you choose be aware that virtualization brings with it steep storage requirements. Think of providing around 1TB of RAID10 storage for 20 guests. VMs do lots of tiny random IOs so for 20 guests split between 2 servers I provide 500GB of RAID10 to each via iSCSI SAN.
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
Not really.
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
I do at work so I can prototype some Linux stuff on my Windows box.
Anyway thank you for your time and any experiences / knowledge you are willing to share :)
I would try both VMware server and Xen on CentOS, if you have 2 servers set them up side by side and plugged into your storage SAN. Run them through their paces, do some benchmarks get a feel for ease of use and maintenance.
When your ready and have a budget you can move up to the commercial versions, ESX and Xen Enterprise.
-Ross
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CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
I work for a school in a New Zealand university and we are wanting to implement Server Virtualization for both CentOS and Windows systems.
Keep in mind virtualization software is moving pretty quickly. 8 months ago Xen didn't migrate fully virtual hosts, now it does. In 5 years the rediculous pricing structure for Virtualization technology will be gone and virtulization will be a commodity where all you pay for are accelorating drivers and managment tools. If you check the virtualization page on wikipedia http://en.wikipedia.org/wiki/Virtualization#Virtualization_examples you'll see a bunch of the questions you should ask to figure out your reasons for going virtual. Try to rank the features you know will help you frequently, and the stuff that's just "WOW! Moving a running server is so cool!". Try to avoid cool stuff for cool stuffs sake. Live host migrations are great if you have dynamic workloads or for the occasion you need to take a physical machine down for firmware/hardware updates during buisness hours, but think of how often you are going to use it and what impact downtimes might have.
From my own research it seems that VMWare or Xen are really the two major products to be considered, are there any others I should be considering ?
Take a peak at KVM (http://kvm.qumranet.com/kvmwiki/Guest_Support_Status). Might not be ready for primetime, but it is pretty favored by the kernel maintainers for simplicty and cleanliness so it's likely to end up going further than Xen. Do you really think the hypervisors and managment software isn't going to endup in hardware?
If it's "Enterprise Level Support" and performance you pretty much have to go with VMware. Realistically, for most companies and workloads way to many things are tagged as "Requiring Enterprise Class", and you can get away with Xen and KVM. The free VMWare Server (aka GSX) is a completely different beast from VMWare ESX, performs pretty terribly, and is almost worthless for production servers. ESX is amazing, and I'd recommend it if you have the money, but I it's like 3K every 2 sockets and needs a san to be very useful. You can quickly rack up 50 grand in hardware and licensing just to get off the ground.
If I had the time, I'd like to try using Xen with an OpenSolaris ZFS iSCSI target as shared storage, but alas I do not have that time.
Is anyone running Linux "Guest" O/S's inside a Windows host ?? And if so can you share your reasons for this?
I've done for people I work with because cygwin is too much of a moving target, or to test that their code compiles and works on both platforms. I also sniffed alot of glue when I was younger.
Patrick
On Tue, 18 Sep 2007, Flaherty, Patrick wrote:
If I had the time, I'd like to try using Xen with an OpenSolaris ZFS iSCSI target as shared storage, but alas I do not have that time.
FWIW, I've had good luck compiling and running the iSCSI target from http://iscsitarget.sourceforge.net/ on CentOS 5. There aren't all the bells and whistles of ZFS, I suppose, but it's pretty simple to set up. Also, given gigabit ethernet and a decent switch, its bonnie++ numbers aren't bad at all.
Paul Heinlein wrote:
On Tue, 18 Sep 2007, Flaherty, Patrick wrote:
If I had the time, I'd like to try using Xen with an
OpenSolaris ZFS
iSCSI target as shared storage, but alas I do not have that time.
FWIW, I've had good luck compiling and running the iSCSI target from http://iscsitarget.sourceforge.net/ on CentOS 5. There aren't all the bells and whistles of ZFS, I suppose, but it's pretty simple to set up. Also, given gigabit ethernet and a decent switch, its bonnie++ numbers aren't bad at all.
IET is pretty much storage independant and can use either block device or file for it's back-end. I use it with LVM, while it isn't ZFS it does provide for more storage management then raw disks or sparse files.
-Ross
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Paul Heinlein wrote:
On Tue, 18 Sep 2007, Flaherty, Patrick wrote:
If I had the time, I'd like to try using Xen with an OpenSolaris ZFS iSCSI target as shared storage, but alas I do not have that time.
FWIW, I've had good luck compiling and running the iSCSI target from http://iscsitarget.sourceforge.net/ on CentOS 5. There aren't all the bells and whistles of ZFS, I suppose, but it's pretty simple to set up. Also, given gigabit ethernet and a decent switch, its bonnie++ numbers aren't bad at all.
Apples and oranges, though. iSCSI is networked block storage. It does not case what filesystem you lay on it. As someone who learned this the hard way, it is not enough to have iSCSI to support live vm migration. If you are look to setup 2+ xen hosts and live migrate amongst them (known as vmotion in vmware-land) you need _shared_ storage filesystem, and ext3 is not that nor is zfs. See http://en.wikipedia.org/wiki/List_of_file_systems#Shared_disk_file_systems for a list of FS that would suitable to lay on iSCSI for this purpose.
Mark D. Foster wrote:
Paul Heinlein wrote:
On Tue, 18 Sep 2007, Flaherty, Patrick wrote:
If I had the time, I'd like to try using Xen with an
OpenSolaris ZFS
iSCSI target as shared storage, but alas I do not have that time.
FWIW, I've had good luck compiling and running the iSCSI target from http://iscsitarget.sourceforge.net/ on CentOS 5. There
aren't all the
bells and whistles of ZFS, I suppose, but it's pretty simple to set up. Also, given gigabit ethernet and a decent switch, its bonnie++ numbers aren't bad at all.
Apples and oranges, though. iSCSI is networked block storage. It does not case what filesystem you lay on it. As someone who learned this the hard way, it is not enough to have iSCSI to support live vm migration. If you are look to setup 2+ xen hosts and live migrate amongst them (known as vmotion in vmware-land) you need _shared_ storage filesystem, and ext3 is not that nor is zfs. See http://en.wikipedia.org/wiki/List_of_file_systems#Shared_disk_ file_systems for a list of FS that would suitable to lay on iSCSI for this purpose.
There is a configuration though that doesn't need a cluster file system to perform live migrations and that is where the Xen VMs write directly to a block device which is an iSCSI target.
-Ross
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-
Clint Dilks -
Flaherty, Patrick -
Mark D. Foster -
Paul Heinlein -
Phil Schaffner -
Ross S. W. Walker -
Steven Haigh -
Timothy Selivanow -
umair shakil