NFS vs iSCSI - Confusing results

drzoidberg33

New Member
Feb 11, 2014
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0
1
I'm trying to decide which is a better option performance-wise but getting some unreliable results when using NFS.

The storage server is running OpenMediaVault with a 4 disk Raid10 array. It's connected via gigabit ethernet on the same switch as the Proxmox node.

For my NFS share I created a LVM logical volume on top of the Raid10 array, then formatted it using ext4 and created a new target for NFS. Set this up in Proxmox as a NFS storage and installed Windows 2012 R2 cleanly on a 256GB partition. I then ran CrystalDiskMark to compare the two storage types.

Initial results varied wildly starting off getting reads of over 1000MB/sec, after a few runs it levelled out but still getting results greater than the available network bandwidth, see below:

Screenshot%202015-05-22%2019.02.21.png


Then I removed all the NFS config and targets, removed the LVM volumes on the storage server and created a iSCSI target pointing to the raw Raid10 array. I then created an iSCSI target in Proxmox and a LVM group on top of that. These results are more along the lines of what I expected, see below:

Screenshot%202015-05-22%2019.49.51.png


Can anyone shed some light on why the NFS storage appears to be faster?

TIA
 
_Probably_ because NFS is using caches and marks data as written to disk before it actually reaches storage server, while ISCSI makes sure it reaches storage before reporting back, that it's written.
 
ON us test was NFS also in all situations the fastest ever. Also with the "sync" option. Interessting would be ZFS over ISCSI, but never tested before.
 

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