Yellow Bricks

by Duncan Epping

nfs

NetApp storage best practices revised!

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About a week ago I wrote about the new version of the NetApp best practices pdf TR-3428. I emailed with Vaughn about the fact that leaving maintenance mode before the reboot might not be the smartest thing to do. Vaughn aggreed and replied that the document would be revised soon.

This would need to go through the normal process which could take weeks. Somehow Vaughn managed to speed things up and just published the new version, 4.4, of TR-3428.

Read the document, even if you don’t own a NetApp there’s still useful info in there! In my opinion it’s one of the best VMware documents I’ve seen so far from a vendor. (Although the Cisco pdf is also a great read!)

New version of the NetApp NFS best practices doc!

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I just noticed that there’s a new version(4.3) of the NetApp on NFS best practices document online. This document has a new best practice in there that I discussed a couple of weeks ago about the “/NFS/LockDisable” and the “prefvmx.consolidateDeleteNFSLocks” settings(Page 14).

As far as I can judge at this point in time the document seems to be also following the VMware guidelines. NetApp suggests running several commands directly on the Service Console to do the desired changes. Although I do agree with their suggested changes, I don’t agree with the order of the procedure.

On page 14 in both “procedures” NetApp suggests that you enter maintenance mode before applying the changes. Which is definitely something I would also suggest. But they also suggest to exit maintenance mode right before you reboot the server. In theory this could lead to VM’s being VMotioned to the host you’re about to reboot. When this happens the VM’s will be killed without any notice, which could lead to all sorts of problems as you can imagine.

So if you’re about to make the changes NetApp suggests, please change the order and do a reboot first and exit maintenance mode when the reboot is completed.

NFS.LockDisable what should it be 1 or 0

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There has been a lot of discussion(check Scott’s take on this) around this advanced NFS setting called “NFS.LockDisable”. In short, you can disable the locking mechanism on NFS volumes with this setting.

In the past NetApp had a best practices document which stated that it should be disabled by setting it to “1”. But, as some noticed this can and probably will result in corrupt file-systems. So this “best practice” mysteriously disappeared from the NetApp VI3 Best Practices guide and a KB Article with the VMware best practice on this setting popped up.

So if you did set “NFS.LockDisable” to 1 please change it back to “0”.  

It might be beneficial to also implement the “prefvmx.ConsolidateDeleteNFSLocks” that Scott discussed along with patch ESX350-200808401-BG. This setting is to avoid long delays when deleting ESX snapshots. This can take up to 30 seconds, which is quite long compared to iSCSI or FC. So you should only implement this fix if you run NFS and do VMware snapshots at them same time and are experiencing these dalays.

I do recommend that everyone with an NFS filer takes a look at the NetApp best practices document because it does contain valuable information, but before you apply it besure that it doesn’t conflict with a VMware best practice!