My client's setup is as follows.
Two Dell Poweredge servers, running ESXi, with 3 virtual machine spread across them. Each has about 2TB of space in SAS disk, which host the virtual machines. These are connected to a NAS via gigabit ethernet, and run nightly backups of the VMs, using ghettoVCB. In the event of one Dell server failing, the VMs will be booted onto the other one from the backups on the NAS, losing at most 20 hours of data.
The NAS I have is a Thecus N5500, with 4 1TB disks in RAID5. It can be configured either to use iSCSI, or NFS, with a filesystem of XFS, ZFS or Ext3.
Looking online, I've seen some bad reviews for iSCSI on ESXi, some people have complained of terrible performance, and as one of the VMs is a Terminal Services server, it needs to be fairly fast. Is iSCSI/vmfs better than NFS, and which filesystem would you use as a backend for it? Does anyone have experience with this NAS and any performance issues with any configuration on it?
Thanks,
~Dentrasi
Edit: ESXi is running from a USB stick on an internal port on the MB.
Best Answer
I'll bet most search results with the keywords ESXi and iSCSI assumes hosting VM's on SAN.
In your case the VM's are hosted on DAS and the iSCSI store is for backup traffic only. The runtime requirements for running VM's over iSCSI and backing up over iSCSI are completely different. You won't find many articles describing ESXi performance over iSCSI file shares.
It's complicated.
I'd go for the simplest solution: NFS. Little if any performance negatives. Much easier configuration, troubleshooting and testing.
But it's not only about the numbers is it? SCSI over IP is just so cool.