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Help with VDI (View) Performance; especially Disk Subsystem

Posted on 2012-09-19
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Last Modified: 2012-09-26
We have a small (right now) VDI (View 5) environment. I have a single host: an IBM 3690 M5 with 144 GB RAM. We are using an IBM DS4700 SANs for our disk subsystem.  At the moment I have about 50 desktops spun up, with about 15 people on at any one time.  Very shortly I'll have close to 40 people on at a time. Our goal by the end of the year is around 100 desktops with 400-500 in the next couple of years.

I realize that we will need more hosts.  However, my problem is with performance. I have tweaked the masters according to the Best Practice guide from VMware. I don't really think the host is holding me back either. I am fully convinced that the DS4700 is NOT where we want to go as we move forward.

I am looking for information about what others have done to get their VDI tweaked as well as possible, especially with the storage; since VDI seems to be very storage intensive.

I'd like to get replies only from individuals who have actually implemented these solutions and not just someone pointing me to some web site. I am NOT interested in some VDI in a box proprietary solution. I am interested in using IBM servers, but the storage can be whatever works the best.
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Question by:jhyiesla
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Andrew Hancock (VMware vExpert / EE MVE^2) earned 1500 total points
ID: 38414308
We've had many issues in this area with VDI deployments, when using conventional storage, either local SAS or SAN based storage. For our VDI deployments we now use Fusion-IO products (SSD) based, to save on electricity, air conditioning, the expensive of SAN deployment, and help us with "VDI storms". e.g. big slowdowns that can occur when a lot of users log into the system at the same time.

Once users boot up, log in and load applications, the storage I/O typically settles down to a minimal level. The IOPS difference between a desktop VM that is booting and after it has booted is extreme, which can make architecting storage for VDI environments a challenge. A typical desktop VM running Windows 7 will generate from 50-100 IOPS while is it booting; once it is running normal workloads, the average IOPS drops to about 5-10. Therefore, to successfully meet the I/O demands caused by boot storms, your storage needs to be designed to handle the worst-case scenario.
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by:James H
ID: 38414310
Before we start, what kind of disks do you have in the DS4700?
Have you done and POC before attempting to deploy production?
Have to metered your VDI clients to see what their peak IOPS usage is?

Just to throw a suggestion out for storage is XIO.
Most issues with VDI are not enough IOPS to support the desktops.

http://xiostorage.com/products/hyper-ise-7-series/#specs_tab

Take a look at them.
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by:coolsport00
coolsport00 earned 500 total points
ID: 38414335
Well, I don't use IBM SANs..I use EMC, but bear with me as I don't think that's your issue (potentially).

I just experienced performance issues myself and have 1/2 the size View deployment as you. If you check the Performance tab in vCenter & select the 'Disk' metric, does it show high latency? If it's above 10ms for continued/prolonged periods, that is more than likely your issue - Disk I/O. Another way to check is SSH into your host and run esxtop. Press "u" and look at the DAVG column.

To resolve my latency/performance issue, first I pinpointed what it was...which was indeed disk-related. My memory & CPU weren't too bad (elevated a bit, but not too bad). Once I pinpointed the cause, I had to come up with a resolution. What the problem was for me was not properly sizing my LUN for the I/O requirement I need. Have you done that?

A typical WinXP workstation can generate about 10-15 IOPS. Multiply that by the # of VM Desktops you created, add in any mgmt VMs you have on the same datastore (and thus, LUN) and that is your IOPS requirement. Depending on the disk type you have in your SAN (i.e. SATA, FC, SAS, SSD) as well as the RAID type, & number of spindles in the RAID, you may not have enough IOPS on your backend to cover the IOPS your desktops require.

To calculate IOPS for your LUN:
First, be aware of how many IOPS a disk "type" can give you:
SATA: 70-90
SAS: 140-180
SSD: 4000

Second, be aware of write penalty per RAID "type""
RAID0 = none
RAID1 = 2
RAID5 = 4
RAID10 = 6

So, to calcuate the IOPS your LUN can give you:
IOPS = (Total VM IOPS determined above x % Reads) + [(Total VM IOPS determined above x % Writes) * Write Penalty of your LUN RAID]

So, for a typical workstation, you get about 60% Reads, 40% Writes, and has about 12 IOPS. To calculate backend IOPS using RAID5 SAS for 20 VMs:
IOPS = (240 x .6) + [(240 x .4) x 4]
        = (144) + (96 * 4)
        = 144 + 384
        = 528

So, your backend RAID that holds your LUN would need to be configured to house at least 240 IOPS (plus other VMs for mgmt, etc). If your backend generates 530 IOPS, you'd be good.

So.....*IF* you are experiencing disk latency, that is something I recommend you look at.

Regards,
~coolsport00
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by:jhyiesla
ID: 38414922
Hancocka, do you have multiple hosts and do you have a Fusion IO card in each?  Also, which card do you have... they seem to have multiple product lines.

Spartan, we have IBM disks 10 K fiber in the DS4700.  Yes we did a POC and that went well, but it was probably too small. No, we have not metered our performance.  Thanx for the XIO link.

Coolsport, thanx for the info. We've not done a lot of monitoring. I do check CPU and RAM and those don't seem to be issues. Most everything I've read says that disk IO is the number one bottleneck for VDI, assuming that you didn't buy low end on the server itself; which we did not. I recently attended a VMUG meeting and that was the overall consensus there as well. We are going to partner with a company who specializes in this, but I always like to get real from-the-trenches suggestions before just handing over my soul to a third party.
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by:coolsport00
ID: 38414936
Another thing you can set up, if you haven't, is CBRC in the View Admin console. (pg. 131 of the Guide: http://pubs.vmware.com/view-51/topic/com.vmware.ICbase/PDF/view-51-administration.pdf).

~coolsport00
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by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1500 total points
ID: 38414970
We've been using and deploying/implenting Fusion-IO products since 2008/2009, Fusion-IO have come along way, and now their products are OEM and rebranded by HP and Dell.

We have been using the IO-DriveDuo 640GB, sized accordingly for the number of VDI desktops required.

http://www.fusionio.com/products/iodrive-duo/

Dell R810 - 128GB 24 Cores - 80 to 100 Concurrent VMs per host
FusionIO IO-DriveDuo 640GB
(~200,000 IOPS and >800MB/s throughput per card)

Yes, we have a card per server.
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by:jhyiesla
ID: 38421465
hancocka, do you couple the fusion IO card with regular storage; what kind of storage do you use?
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LVL 124
ID: 38421480
Folders are redirected on CIFS shares on NetApp Filers.

but no additional storage is used to support VDI workstations. Fusion-IO cards for us traditionaly replaces local storage or SAN storage, because it's too slow.
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by:jhyiesla
ID: 38421591
what do you do if you'd lose a host?  Do the FIO cards hold the file info after power is gone?  can you vMotion OK, or is that even in your plan?
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by:Andrew Hancock (VMware vExpert / EE MVE^2)
Andrew Hancock (VMware vExpert / EE MVE^2) earned 1500 total points
ID: 38421676
there is enough capacity designed into the farm, to have two host failures.

Yes, storage is maintained after a power off.

Now that SANs can use SSDs, we are starting to investigate these options, BUT these are expensive, expensive to purchase initially, cost money to run, Heat and AirCon, Space, Training Administration, and most of our clients, want an easy life!
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by:jhyiesla
ID: 38432584
Coolsport00, apparently the CRBC thing is not available in View 5.0; it appears to just be a 5.1 thing.

hancocka, looks like we are going to initially get a single Fusionio card for our host.  If that works out, we will probably do the same thing in our next host.

We also looked at Nimble Storage technology for centralized storage and it looks promising as well. If the FIO card doesn't do it, we may look at them for centralized storage or we may use them when it's time to replace server storage.
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by:jhyiesla
ID: 38437445
Thanx...
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