Mass Storage Server

building a mass storage server, but unsure whether it is better to go for most space per system, or most space per U.

Looking at making 2 storage servers sometime in the future, one more for performance (15k 300gb SAS drives) and another for more storage (bunch of 1TB SATA drives). Both would act as iSCSI targets and likely have multiple gigabit ethernet connections bonded together.

Some options I am looking at:

1) HP DL320s provides 12 drives in 2U, or 6 drives per U. Upgrade it to 512mb batter backed cache and it does RAID6. Probably the densest storage U.

2) Supermicro has a 3U chassis that does 16 drives, or 5 1/3 drives per U. Pair that with one of the newer Areca SAS controllers and up to 2gb onboard cache and it should scream.

3) Supermicro also has a 3U chassis with 15 drives... just 5 drives per U, though it is ~$200 cheaper than the 16 bay one. Probably a mute point, since either way, it is less storage per server and less storage per U.

4) Get a simple 1-2U case and use external JBOD enclosures. Could put in multiple RAID cards, hook it up to multiple 3U 16 bay enclosures, and really squeeze in a lot of storage per server.

Anyone else been in a similar boat? Overall, not looking for a real dense configuration, with like 10-20 servers of this config, so don't *need* to squeeze in more TB per U, but it is one way that I've been looking at it.

Perhaps, in a way torn between the pre-built DL320s and the white label Supermicro approach. DL320s is a nice packaged system, support, iLO, etc. Supermicro allows more space and likely more performance (Areca likely better than the HP SmartArray), but no iLO, no single source for support, etc.