Tag Archives: esx

EMC World 2012 – Thoughts on preparing for a VDI deployment

We’re in the process of testing the deployment of VDI now so I attended a session about preparing for a deployment.   As I mentioned in my previous post, I’m not an expert on any subject after attending a one hour session, but I thought I’d share my thoughts.

The most important take away from the session was mentioned near the beginning – for a truly successful deployment you must do a detailed desktop IO analysis.  It’s important to have a firm grasp on the amount of desktop IO that your company requires and a detailed analysis is the only way to gather that info.   There are “rules of thumb” that can be followed ( 5 IOPs for light users, 10 IOPs for medium users, and 20 IOPs for heavy users), but you could easily end up either over-allocating or under-allocating without knowing the actual numbers.  Lakeside software and Liquidware labs were mentioned as vendors who provide software that does such an an analysis, however I’ve never heard of either of them and can provide no information or feedback on their services. There’s a good free VDI calculator available at http://myvirtualcloud.net/?page_id=1076.  Once you have a good grasp of the amount of IO you’ll need to support, scaling for the 95% percentile should be your target.

What’s the best way to prepare for VDI on a VNX array?  If you conclude from your analysis that your desktop environment is more read intensive, consider hosting it on storage pools that utilize FAST VP with EFD and FastCache.  Using VMWare’s View Storage Accelerator and EMC’s VFCache would also be of great benefit.  If your environment is more write intensive, focus on increasing the spindle count (even at the expense of wasted capacity).  All of the other items mentioned for read intensive environments still apply and would be beneficial.

Final thoughts:

– If you’re using Windows XP make sure disk alignment is set correctly.  If it’s not, you could see up to a 50% penalty in performance.

– Image optimization is very important.  Remove all unneeded services.

– Schedule your normal maintenance operations off hours.  Running patches and updates during business hours could cause the help desk phones to light up.

– Using NFS vs. block is a wash performance wise.  NFS is currently better for scaling up, however, as it allows for up to a 32 node cluster vs. only 8 for block (on linked clones).

– Desktops tend to be write heavy.  FAST VP is great!

VMWare/ESX can’t write to a Celerra Read/Write NFS mounted datastore

I had just created serveral new Celerra NFS mounted datastores for our ESX administrator.  When he tried to create new VM hosts using the new datastores, he would get this error:   Call “FileManager.MakeDirectory” for object “FileManager” on vCenter Server “servername.company.com” failed.

Searching for that error message on powerlink, the VMWare forums, and general google searches didn’t bring back any easy answers or solutions.  It looked like ESX was unable to write to the NFS mount for some reason, even though it was mounted as Read/Write.  I also had the ESX hosts added to the R/W access permissions for the NFS export.

After much digging and experimentation, I did resolve the problem.  Here’s what you have to check:

1. The VMKernel IP must be in the root hosts permissions on the NFS export.   I put in the IP of the ESX server along with the VMKernel IP.

2. The NFS export must be mounted with the no_root_squash option.  By default, the root user with UID 0 is not given access to an NFS volume, mounting the export with no_root_squash allows the root user access.  The VMkernal must be able to access the NFS volume with UID 0.

I first set up the exports and permissions settings in the GUI, then went to the CLI to add the mount options.
command:  server_mount server_2 -option rw,uncached,sync,no_root_squash <sharename> /<sharename>

3. From within the ESX Console/Virtual Center, the Firewall settings should be updated to add the NFS Client.   Go to ‘Configuration’ | ‘Security Profile’ | ‘Properties’ | Click the NFS Client checkbox.

4. One other important item to note when adding NFS mounted datastores is the default limit of 8 in ESX.  You can increase the limit by going to ‘Configuration’ | ‘Advanced Settings’ | ‘NFS’ in the left column | Scroll to ‘NFS.MaxVolumes’ on the left, increase the number up to 64.  If you try to add a new datastore above the NFS.MaxVolumes limit, you will get the same error in red at the top of this post.

That’s it.  Adding the VMKernel IP to the root permissions, mounting with no_root_squash, and adding the NFS Client to ESX resolved the problem.