XenServer vs ESXi

[Kamran7860]

Hi all

 

I am planning to virtualise our servers in the summer. We only have 7 servers but there all getting old, so planning to get 2 HP DL180 G6's.

 

Storage will all be local RAID as we do not have the money for a SAN and backups will be manually exported to a NAS that we already have.

 

I just can’t make my mid up which one to go for Citrix XenServer or VMware ESXi. Just wanted to know what people think of both of these products.

 

From what I can see is that Citrix has a centralised management console plus live motion but do we really need it for 2 servers. Also what are conversion tools like for both of them.

 

 

Any advice or suggestions would be appreciated.

 

Thanks

Edited May 28, 2009 by Kamran7860

[nicholab]

Use Falconstor (Network Storage Server Virtual Appliance http://www.falconstor.com/en/pages/?pn=NSSVA) or Lefthand networks software to create a virtual SAN!

[Duke]

Kamran7860 - Are you going for the 'free' or 'paid-for' solutions from Citrix and VMware? I assume you're talking about a free solution of ESXi without vCenter and the 'non-Essentials' version of XenServer.

 

Personally based on my testing, I'd go with Xen if I was going for a free solution and VMware vSphere/ESX for a paid-for solution. I found Xen's free solution to have better and less cut-down features than VMware's, and it's also quite a bit easier to set up and configure. On the flip side, VMware vSphere/ESX with vCenter is a much more enterprise-level solution with more advanced features. I guess it comes down to what you can afford and what features you consider essential. If you're going with local storage rather than a SAN then you're not going to be able to make use of the failover functionality anyway so the free version of Xen may well do everything you need.

 

(I'm assuming there's no budget available for a 'cheap' SAN like a Sun 7110?)

 

Cheers,

Chris

[Kamran7860]

Yep i am looking at the free solutions. Ive just been testing them and i like both. The only problem is the

 

XenConverter its not been able to convert all of the Test servers. VMware vCenter Converter on the

 

other hand has done them all with no problems.

 

 

Nope no budget for a SAN yet but maybe in the in a year or two. What do you think for the hardware

 

HP DL180 G6's or Sun Fire X2200 M2's. I am not sure if ESXi will work on the HP. However the SUN can

 

according to the sales guy.

[Duke]

We're mainly a Dell shop here, and I'd definitely recommend looking at them for servers. HP have never wowed me with their stuff, but if you've already got a lot of HP kit then it might be easiest to stick with them. They should really have hardware that's VMware certified so just give them a shout and I'm sure they can find the right server for you. I've never had any Sun servers, but the Sun 7410 we've got has really impressed me. It's got 24 drives in it and it's the coolest running thing in the server room, it actually chucks out cool air!

 

Cheers,

Chris

[Soulfish]

 

Nope no budget for a SAN yet but maybe in the in a year or two. What do you think for the hardware

 

HP DL180 G6's or Sun Fire X2200 M2's. I am not sure if ESXi will work on the HP. However the SUN can

 

according to the sales guy.

 

I'd go for the Sun hardware based on the fact that the out of band management is great on Sun servers. Everything is included, unlike with other companies where you have to pay to unlock certain features!

 

Sun also seem to pack much more then everyone else into the same size space

[Butuz]

I think if you're quick you may be able to get a matching grant application in to Andy at Cutter (his username on these forums is linescanner).

 

By not using a SAN you're missing out on one of the most important and beneficial reasons for virtualising - the ability to failover virtual machines from one physical host to another in a matter of minutes.

 

I would reconsider not using a SAN to be honest - if one of your physical hosts fails for whatever reason all the VM's on it will be down, and stay down until it can be repaired / replaced (providing you have actually managed to back up your VM images!)

 

Butuz

[jcollings]

What do you think for the hardware

 

HP DL180 G6's or Sun Fire X2200 M2's. I am not sure if ESXi will work on the HP. However the SUN can

 

according to the sales guy.

 

We have a couple of EXSi setups on HP DL140 G3 and it works really well.

[pod]

Checkout backing up your virtual machines on Esxi, isn't straight forward in my experience.

[budgester]

By not using a SAN you're missing out on one of the most important and beneficial reasons for virtualising - the ability to failover virtual machines from one physical host to another in a matter of minutes.

 

I would reconsider not using a SAN to be honest - if one of your physical hosts fails for whatever reason all the VM's on it will be down, and stay down until it can be repaired / replaced (providing you have actually managed to back up your VM images!)

 

Butuz

 

So I can understand what you propose can you confirm:

 

You store the host images stored on the SAN.

On the virtualisation host you mount the SAN and run the image.

 

And could the virtual servers also point to another storage area on the SAN e.g. user areas.

 

I'm assuming something like iSCSI for the SAN ?

 

Regards

 

Budgester

[Duke]

You store the host images stored on the SAN.

On the virtualisation host you mount the SAN and run the image.

 

And could the virtual servers also point to another storage area on the SAN e.g. user areas.

 

I'm assuming something like iSCSI for the SAN ?

 

Figured I'd drop a quick reply as no one else has yet:

 

On the SAN you make make some space for your virtual machines, be it an iSCSI LUN or a NFS filesystem. Within the Xen or ESX management console you add/attach the storage which makes it available to your physical hosts. When you create a virtual machine its virtual hard disk files are then stored on the SAN which is independent from any of the hosts. If a physical host dies then another one automatically takes over and boots up the virtual machines from the SAN. Your downtime goes from several days to get a server running again to under two minutes.

 

Yes, there's no reason why your virtual machines can't use the SAN at a file-level too for storage (or block-level if you wanted iSCSI attached storage). You treat your virtual machines just like a physical one, and you could map a drive on them too the SAN, or even use CIFS to have your client PCs and users working directly on it.

 

A SAN is typically block-level, which will usually be iSCSI. However, if you're looking at a unified storage system like the Sun S7000 range then you get iSCSI, NFS and CIFS all free. NFS apparently gives better performance than iSCSI with ESX, but the principal is the same. With CIFS your Windows users can directly access the box with \\san\share.

 

Hope this helps,

Chris

[boomam]

All of VMWares stuff works very nicely with HP stuff.

Two reasons as to why:

1) Its says on their site.

2) The conference i was at the other day with HP/VMWare heavily advertises the 'link' that the two companies and their products have.

 

.

[Theblacksheep]

Checkout backing up your virtual machines on Esxi, isn't straight forward in my experience.

 

Do it with a script.

[midus]

Kamran,

 

I've tested ESXi with OpenFiler, FreeNAS, StarWind iSCSI SANS

 

Openfiler is by far the best performing SAN.

 

We're about to go into a live test in a production environment in my company.

 

Just FYI, SAN is still possible on a low budget.

[sirsir]

We have been fortunate enough to have taken advantage of the Sun advantage program... 2 4150 Sunfires with 56 Gb Ram each for the price of 1.... linked to a Dell iscsi target. 6 servers on each with failover, HA etc.

Yes and space for data areas. 2 servers are Novell. Implementing this month....

 

Oh yes ESX enterprise on both..

Edited June 17, 2009 by sirsir
left out vital info

[Kamran7860]

We only need a about 2 to 3 TB of storage for the virtual servers after RAID (ideally RAID 5).

 

Has anybody used the QNAP TS-509 Pro it can be used as a iSCSI target server, it also has dual gigabit NICs. Ive seen some very good reviews about this NAS. Any ideas? or is a custom Openfiler SAN better.

 

As for Openfiler anyone running it on a HP ProLiant DL180 G5.

 

Thanks

[saywhat]

I think if you're quick you may be able to get a matching grant application in to Andy at Cutter (his username on these forums is linescanner).

 

By not using a SAN you're missing out on one of the most important and beneficial reasons for virtualising - the ability to failover virtual machines from one physical host to another in a matter of minutes.

 

I would reconsider not using a SAN to be honest - if one of your physical hosts fails for whatever reason all the VM's on it will be down, and stay down until it can be repaired / replaced (providing you have actually managed to back up your VM images!)

 

Butuz

 

We are looking into this also.

 

However what happens if your SAN dies?? I know it will be RAID etc, but if the actual SAN controller dies, then surely ALL VMs and data goes down until you can reisntall the RAID into another box??

[Butuz]

We are looking into this also.

 

However what happens if your SAN dies?? I know it will be RAID etc, but if the actual SAN controller dies, then surely ALL VMs and data goes down until you can reisntall the RAID into another box??

 

Yep a valid point indeed. In order of things most likeley to fail:

 

1) Disk Drives - moving at 10k rpm on some ball bearings these are most likeley to fail. So hot swap is a must, and use enterprise level SAS drives rather than budget SATA drives if you want the highest disk reliability.

2) FANs - again spinning at a few thousand RPM on ball bearings, these can fail, make sure they are hot swappable and more importantly, make sure the case design is clever enough for you to be able to hotswap them in situ, in the rack cabinet.

3) O/S. Can become corrupt. If your SANs OS goes down then so does your SAN.

4) Electronics - the storage controller and network card come under here - both items which could take your entire SAN down - BUT microprocessor devices with no moving parts are ultra reliable and I wouldnt expect a controller or NIC to fail within a 5 year lifespan, it is extremely rare. Can be offset by multiple NICs and multiple controllers if your totally paranoid.

 

 

I would come at it from this angle:

 

1. Ideally for maximum disaster proofing / recovery you want to have 2 mirrored SANs spread apart in different buildings. This is the ideal scenario as if one san dies you have the other one which you can connect to.

 

2. A SAN is a dedicated storage device, with battery back up cache and possibly solid state cache drives. As such it should theoretically be far more reliable than just a normal windows box shoved full of disks. You should run in Raid 6 with a hot swap drive so that your SAN can sustain two concurrent drive faliures, and you should make sure the SAN has good same business day warranty on it, and that it is set up to alert you the minute it notices something going wrong.

 

3. If your consolidating from local storage on many older servers to shared storage on a new SAN then really you are giving yourself a big upgrade in relaibility - I'd trust a Sun 7110 over all of the old servers with old SATA / SCSI hard drives we had.

 

Butuz

[Guest monkeyx]

Hmm.

 

We could not afford a SAN and a virtualisation solution in a single fiscal year.

 

We decided to virtualise first after coming accross Promox VE. We have created a cluster of machines where we can migrate machines within the cluster. Moodle even migrates in real time Also allows for easy backups etc.

 

It gives far more functionality the ESXi and was we also felt it was better then Xensource and Xen open source.

 

Proxmox VE adds a great front end to openVZ and KVM that can virtualise both Windows and Linux machines.

 

We will add a SAN (openfiler) solution to this next year, but I would see the SAN as single point of failure unless it was mirrored. We have got a resilient solution spread accross 3 servers in a single cluster.

 

Given that many of servers are now virtualised has given us greater resillience and flexibility for the management of our infrastructure. A SAN would enable us to provide greater IO and run more VMs per server. If we lost the SAN then we would lose all VMs! So I think I will still balance the server load between local and SAN storage.

 

We also saved a reasonable amount of money not using the extended commercial versions of Xen and VMware.

 

I do not think there is a right or wrong answer for whether to use a SAN with VMs. Depends on your own server loadings and IO requirements as to which solution will work best for you.

Edited June 22, 2009 by monkeyx