network-attached-storagestoragestorage-area-networkvirtualizationxenserver
I'm about to deploy XenServer on a DELL R900 and haven't finalized on the Storage yet.
Would typically be running like 40 VMs on the server with requires about 2TB of storage.
What should I choose Local Attached Storage, NAS, SAN? Need to build a soultion that gives a better performance, scale-up and backup options.
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.
First it is best to define the difference between a block device and filesystem. This is easier grasped if you are familiar with UNIX because it makes an objective distinction between the two things. Still the same applies to Windows.
/dev/sda for a disk or /dev/sda1 for a partition on that disk.mount /dev/sda1 /mnt/somepath.With those terms in mind it's then easier to see the distinction between the following.
Best Answer
If you have just a single R900 server to dedicate to this project then there is no reason not to use local storage - it's going to be the cheapest and the fastest. I will not turn this discussion into a disscusion about if this is something you should do or not :-) 40 VM's running on a single server may or may not have the preformance/redundency that you require - that is another topic.
SAN storage is required when you have multiple servers dedicated to hosting your VM environment. The shared nature of the SAN allows each server to have access to the VM files. This allows things such as vMotion (or Live Migration).