NFS and ESXI

[some12]

I am experiencing horrible performance with my nfs datastores in esxi, as expected when reading about the sync options. Now I have a question, if say I create a second nfs share, which is not used as an esxi mount, and mount this in a vm with NO sync, what would the possible consequences be for me? The performance is around 20 times better with no sync... The way I understand it, is that ZFS also syncs, so it should be fine. On a power loss the most I could imagine is that a single file which is writing atm. could be corrupted. This I assume is the same that we would expect if writing something with samba and experience a power loss.

 

[Dave Genton]

yep, terrible performance with ESXi which is well documented. Stability and safety of you data is at risk as you stated, nothing more, nothing less its a gamble. I've changed the sync myself in the past and watched the data fly by so much faster but in the end I always put it back :)

 

[Ericloewe]

I am experiencing horrible performance with my nfs datastores in esxi, as expected when reading about the sync options. Now I have a question, if say I create a second nfs share, which is not used as an esxi mount, and mount this in a vm with NO sync, what would the possible consequences be for me? The performance is around 20 times better with no sync... The way I understand it, is that ZFS also syncs, so it should be fine. On a power loss the most I could imagine is that a single file which is writing atm. could be corrupted. This I assume is the same that we would expect if writing something with samba and experience a power loss.

ZFS syncs when the transmission requests a sync. You're looking at a few seconds of lost data - plenty to ruin whatever you were doing (along with your day). This applies to power losses, panics and similar situations.

 

[some12]

First off thanks for the answers, but I have a couple of more questions

• My top goal is not to ruin my pool. Will I be able to destroy my pool with NFS / iscsi with and without sync?
• If I use NFS as a datastore and have sync ON, will I be able to corrupt my vmdks?
• If I use NFS as a datastore with sync OFF, I have the chance of corrupting my vmdks, which is why this method is not recommended, correct?
• If I mount an NFS share with sync OFF on any system, be this a virtual machine or a normal machine, I will be able to corrupt single files, but not the whole pool, correct?
• What is the difference in risk I am taking if I mount a share via NFS or samba?

I can live with a few seconds of lost data, even though it likely will ruin my day ;)
Thanks!

 

[Ericloewe]

I think the pool would survive, with damage being limited to the files being written.

• If I use NFS as a datastore and have sync ON, will I be able to corrupt my vmdks?
• If I use NFS as a datastore with sync OFF, I have the chance of corrupting my vmdks, which is why this method is not recommended, correct?
• If I mount an NFS share with sync OFF on any system, be this a virtual machine or a normal machine, I will be able to corrupt single files, but not the whole pool, correct?
• What is the difference in risk I am taking if I mount a share via NFS or samba?

• There's always stuff that can go wrong, but generally the answer is no.
• Yes, you'd lose the transaction group, which would probably mean a corrupted virtual disk image.
• I believe so, yes (not 100% sure and again, there's always stuff that can go wrong. sync only helps to certain extent)
• Should be the same thing, all else being equal