On Tue, Feb 7, 2012 at 7:22 PM, Kurt Buff <[email protected]> wrote: > I've got a new-ish (January) EMC VNXe 3100, and have run into a > troubling limitation - in use as an iSCSI device, it doesn't support > LUNs larger than 1.99tb.
Find out what other ways can you use it (other than iSCSI), and what the limits are then. That information may be helpful. > According to a post by EMC staff on their community forum, it's > doe to the implementation of the SCSI II protocol. I've been digging around trying to find a concise, authoritative, single-location answer to this. Not having much luck satisfying all of those conditions. But if I'm interpreting the SCSI-2 specification correctly, the biggest command block defined has a 32-bit LBA field. As such, you're limited to 2^32 blocks of storage. Given the typical block size of 512 bytes, that works out to 2^41 bytes, or exactly 2 TiB. So there may be some validity to what they're saying. Of course, the SCSI-2 specification was published in 1994, almost twenty years ago, so one has to ask why they're using such an old document. Other block sizes (bigger than 512 bytes) are perfectly acceptable to SCSI -- even SCSI-2. So one could get larger capacities by increasing the block size. EMC would have to implement that, of course. I also don't know if such a block size would be acceptable to the Windows iSCSI stack. Later SCSI specs defined still larger command blocks, with 64-bit LBAs. -- Ben ~ Finally, powerful endpoint security that ISN'T a resource hog! ~ ~ <http://www.sunbeltsoftware.com/Business/VIPRE-Enterprise/> ~ --- To manage subscriptions click here: http://lyris.sunbelt-software.com/read/my_forums/ or send an email to [email protected] with the body: unsubscribe ntsysadmin
