A few weeks ago, I worked on setting up a Buffalo Terastation 3400 to store VMWare ESXi VM images.
For flexibility reasons, I wished to use NFS instead of iSCSI, however I discovered that performance was absolutely dismal. Initially, I was only getting 6MB/s write throughput via NFS on ESXi. However, mounting the same NFS mount from a Linux VM on the same ESXi instance, I would see 40MB/s!
After a couple of days of fruitless efforts and a call to Buffalo Tech Support, I finally found a solution.
1) Make sure the Terastation NFS is in kernel mode, otherwise it won’t work at all with ESXi.
2) Upgrade the firmware. Don’t believe the TS web GUI when it says its firmware is up-to-date. Mine said it had the latest, however when Buffalo USA Tech Suppport sent me to their website, I found a much newer version available.
In my case, this upgrade boosted write performance from 6MB/s to 40MB/s.
3) Changing from RAID 5 to RAID 10 decreased my usable space, but boosted write throughput to approx 70MB/sec