SSDs and VDI

[localzuk]

Indeed, XenDesktop is clever with the provisioning but as you say the storage becomes the bottleneck. You're then either at the point of SANs with flash acceleration or a single server with local storage, not something I'd like take a chance on if all my clients were depending on it...

Considering the costs involved here, a server with 144GB of RAM and 2x SSDs capable of supporting VDI would come to around £5k. So, for £10k, you could easily have 2, with double the capacity required.

So, if one died, your remaining one would have the space to run everything you need anyway.

[jamesfed]

Indeed, XenDesktop is clever with the provisioning but as you say the storage becomes the bottleneck. You're then either at the point of SANs with flash acceleration or a single server with local storage, not something I'd like take a chance on if all my clients were depending on it...

Our 1Gb Flash Back cache does a grand job for keeping things ticking over nicely
Next step will be to fill the server with a full stack of HDDs when we expand our Virtual Desktop estate.

[jamesfed]

Considering the costs involved here, a server with 144GB of RAM and 2x SSDs capable of supporting VDI would come to around £5k. So, for £10k, you could easily have 2, with double the capacity required.

So, if one died, your remaining one would have the space to run everything you need anyway.

I know I've said it before but if you want to go local storage take a look at Kaviza - its made for local storage runs on XenServer and uses Citrix HDX. It keeps things simple as well because you don't need a seperate connection broker.

[Soulfish]

If you're rolling your own storage server using comodity parts I'd probably opt for a minimum of 4 SSDs in a Raid-10 array. I'd give a guess at a IOPs utilisation of 1,000 -2,000 for that many desktops asuming all users logged in and doing things. Boot-up IOPs would be much higher (probably around 10,000 - 15,000) but can be managed by booting up desktops over a period of an hour at the start of the day/peak time.

http://jimmoyle.com/wordpress/wp-con...p_Dive_1_0.pdf is a good read for some W7 specific information. Estimate IOPS for Virtual Desktops » ocb - Citrix Community and Deploying XenDesktop without a SAN » ocb - Citrix Community are also some good documents/blogs to read on deploy XenDesktop and IOP requirement planning. The last link is focused on deploying XenDesktop without a SAN and just what you'd need to do that.

One other option is to use XenServers intellicache feature with XenDesktop. See XenDesktop 5 with IntelliCache cuts VDI storage costs in half » ocb - Citrix Community for more infomation. Wouldn't necessarily need SSDs then - either for the SAN or for the local disks.

[localzuk]

I know I've said it before but if you want to go local storage take a look at Kaviza - its made for local storage runs on XenServer and uses Citrix HDX. It keeps things simple as well because you don't need a seperate connection broker.

Going from your email though, it seems to cost about 3x as much as XenDesktop. Meaning 160 clients go from about £5k in licenses to £15k in licenses.

[localzuk]

One other option is to use XenServers intellicache feature with XenDesktop. See XenDesktop 5 with IntelliCache cuts VDI storage costs in half » ocb - Citrix Community for more infomation. Wouldn't necessarily need SSDs then - either for the SAN or for the local disks.

How does that work? Does it need something specific to work, hardware wise?

[Soulfish]

How does that work? Does it need something specific to work, hardware wise?

Hardware wise anything that runs XenServer with local storage. They talk about using SSDs to cache, but I imagine you could also use fast disks as well. Other then that you'd need a SAN to store the base image. Essentially all it's doing is running some smart algorithms to cache the VDI golden image on the local servers rather then having them all ready directly from the SAN.

[localzuk]

Ah, I've just read about it and it does local caching of blocks from the 'master' image - it can do it to RAM, SSD or hard disk. It isn't suited to 'personal' images though, as the write-cache which is created on the local host is wiped on shutdown, rather than being copied back etc...

And again, it assumes we end up with a SAN. Which we don't have and don't want to splash out and buy.

[jamesfed]

Ah, I've just read about it and it does local caching of blocks from the 'master' image - it can do it to RAM, SSD or hard disk. It isn't suited to 'personal' images though, as the write-cache which is created on the local host is wiped on shutdown, rather than being copied back etc...

And again, it assumes we end up with a SAN. Which we don't have and don't want to splash out and buy.

Ultimately if you are looking at using this in a classroom then the issue with personal images dosn't matter as over night you will destory all the desktops and recreate them.

[localzuk]

Ultimately if you are looking at using this in a classroom then the issue with personal images dosn't matter as over night you will destory all the desktops and recreate them.

It would be used for both in-class and for admin.

[VirtualTal]

Hi there, Tal Klein from Citrix here. I'm chiming in because I think in your particular XenDesktop VDI situation you'd probably reap the benefits of XenServer IntelliCache. There's a pretty decent article about it from Brian Madden. The reason I say that is because in your case with going pure VDI for less than 200 desktops, you might want to use MCS (Quick Deploy) instead of PVS (Provisioning Services). With MCS+IntelliCache you'd get similar benefits to PVS with less infrastructure. Also, to guide you on storage, the XenServer storage HCL list is here.

I'll try to stay active on this forum because I see a lot of interesting discussion, but if you ever need technical help re: XD feel free to send me a DM. I may marketing in my title, but I come from a long engineering background - my job is mostly to keep marketing (both ours and our competitors) honest

-Tal

[localzuk]

Hi there, Tal Klein from Citrix here. I'm chiming in because I think in your particular XenDesktop VDI situation you'd probably reap the benefits of XenServer IntelliCache. There's a pretty decent article about it from Brian Madden. The reason I say that is because in your case with going pure VDI for less than 200 desktops, you might want to use MCS (Quick Deploy) instead of PVS (Provisioning Services). With MCS+IntelliCache you'd get similar benefits to PVS with less infrastructure. Also, to guide you on storage, the XenServer storage HCL list is here.

I'll try to stay active on this forum because I see a lot of interesting discussion, but if you ever need technical help re: XD feel free to send me a DM. I may marketing in my title, but I come from a long engineering background - my job is mostly to keep marketing (both ours and our competitors) honest

-Tal

Thanks for the info. That compatibility list doesn't really help as I'm specifically looking to remove the SAN aspect from the job.

[VirtualTal]

Got it. Well, we also have an HCL for storage controllersr for your server - so any of these with local storage would also support IntelliCache thereby enabling you to use Quick Deploy instead of PVS with "different but similar" benefits to IOPS.

-Tal