More modeling issues

I recall we discussed that earlier, that our ReclaiMe Free RAID recovery software (and pretty much any generic RAID recovery software, like Runtime's RAID Reconstructor) does not actually work with RAIDs. It works with models of RAIDs instead. Data recovery service view on RAID5 more like "disks (by specific vendor), controller (also by specific vendor), and cables". The software sees it like

1 2 P
3 P 4
P 5 6

and pretty much nothing else.

The problem arises when the actual data does not match the model used in software. The synchronous array (below) cannot be described in terms of the asynchronous model (above).

1 2 P
4 P 3
P 5 6

So the software has to acount for all possible models of the RAID 5, of which there are quite a number.

We're currently working on automatic analysis of the so-called delayed parity arrays, used in HP SmartArray controllers. This subtype of RAID5 does effectively have two distinct stripe sizes, one for data and the other (larger) one for parity, with the array looking like

1 2 P
3 4 P
5 P 6
7 P 8

Would be nice to account for that, because I'm not aware of anything capable of recovering this type of array automatically.


Popular posts from this blog

QNAP revisited

Hotspare vs. Hotswap