Storage strategies

John mentioned in the RAID Cache Battery Source thread about NAS and iSCSI and the System i. I am facing some decisions about storage and server consolidation in the near future (maybe 6 months or so) and I am trying to plot a strategy that will try to kill as many birds with one stone as possible.

I want to lead with the storage first because that is where I have the most pain. I have 2TB of RAID 5 storage scattered over 3 or 4 Wintel/Linux servers, plus 220 Gb of storage on System i / iSeries (520 and 270). We have been adding disks to each of the servers over time and have had to swap tape drives for some with greater capacity over time and I am frankly getting tired of individual system upgrades. We need to consolidate and rationalize the approach.

I know enough about SAN, NAS and iSCSI to be dangerous so what I am working with is purely conceptual. I have no experience (yet) with this stuff.

What I envision is an iSCSI storage system to start. I have one server that I am just about to replace (rack mounted), and I could use iSCSI as the storage solution for it. What I'd like to do is continue to add drives to the iSCSI storage device as I retire each server. Some servers will be virtualized and some will be metal to metal replacements but in all cases I would rather add disks to the iSCSI device and then use iSCSI interfaces in each server rather than add disks to the servers. I may even look at a blade server rather than rack mount servers because of the inevitability of a System i blade offering.

Does this approach make sense, particularly with a System i in the mix? And, that System i is due for replacement late next summer/early fall (I know the dear old 270 won't be able to play) I recall reading that the System i can be an iSCSI target but not an initiator (true?). The whole approach is to have a single storage device where the disks are virtualized for use by the servers (both metal and virtualized). Then a single tape backup strategy and a single blade center hosting the servers. That gets me back to a simplified hardware/storage/backup strategy.

Where are the gotcha's if this is feasible?

Pete