Data Recovery Weekly

If you want some unusual RAID layouts, call Promise. So far, Promise controller has the most bizzare RAID 6 variation we've seen, and also gave us a nasty surprise with RAID 1E. Typically, RAID 1E would be laid out as follows 1 1 2 2 3 3 4 4 5 5 6 6 (the above is so-called NEAR layout) or 1 2 3 4 5 6 7 8 9 3 1 2 6 4 5 9 7 8 (the above is FAR layout). Now Promise combines the best of both worlds to produce a third variation (Promise 1E layout) 1 2 3 3 1 2 4 5 6 6 4 5 Looks promising , doesn't it? So, the implementation of RAID 1E recovery capability in ReclaiMe Free RAID Recovery ( www.FreeRaidRecovery.com ) is delayed until we figure out how to handle this one.

With a RAID recovery , certain exotic RAID types can be recovered using the same basic algorithms, because these exotic RAID types can be reduced to one of the three basic types (RAID0, RAID1, and RAID5). The list goes like this: RAID 1+0 or 0+1 can either be reduced to RAID 0 by removing mirrors ( near layout), or can be recovered as a RAID 0 straight away ( far layout). RAID 5E or RAID 6E can be recovered as a RAID 5 or RAID 6 respectively, because all the extra data is at the end of the array. RAID 5EE can be recovered as RAID 6 with one of the sets of parity corrupt. RAID 4 is actually a variation of RAID 5 where parity does not change position across rows. The array types requiring special processing are RAID 1+0 using offset layout and RAID 1E.