VMWare ESX Storage Upgrade solutions
If you have any plans at all to scale out your ESX cluster, and it sounds like you are as you're considering vmotion and vcenter, you do need to pay attention to your I/O channel. SATA is OK for one or two servers pounding it, but if you ever plan to go past two it won't scale well without serious engineering.
Unfortunately, 'serious engineering', costs a lot of money. As do SAS-based arrays. In the long run, SAS will give you good performance for longer on an equivalent amount of disk. The SATA architecture doesn't handle massively random I/O as well as SCSI based disks (of which SAS is one). You can compensate for this in array hardware with larger caches to help de-randomize the I/O, but there will still be that fundamental limit at the base. There is a reason the big array vendors suggest that SATA drives not be used in an 'online' capacity (ESX hosts, file-servers) and instead suggest 'nearline' (Backup-to-disk, email archive, that kind of thing).
I would suggest it may be the time considering the iSCSI SAN solution. DroboPros is really a good affordable option for that matter. However, if the budget permits, I would also recommend implement SAS disks instead of SATA. The performance will be a lot better, especially when the SAN is going to host several or maybe more than 10 guests on it.
I have a iSCSI SAN w/ SAS disks in place but I am at the point where I need to upgrade the space too. So I upvoted this question and will be looking at closely as well to see if other guys have any suggestions.
What I help run:
- 4 ESX 3.5 Servers
- 3 Equal Logic SANS (From Dell)
- 2 Dedicated Switches
Being able to vmotion machines from one server to another has helped many times. So many I cannot count. We even had to replace the mobo on one of the servers. No down time for the VMs.
If you have more than one ESX server, seriously consider a good SAN (w/ iSCSI), with good disks (SAS). Spending a little extra on good equipment will save you a lot of heartbreaks, and headaches, later on.