Data Storage - Exact checksums used for mirroring and RAID

Author

Exact checksums used for mirroring and RAID

Nick Maclaren

2004-08-09, 5:45 pm

We have had trouble with mirroring, which has the result that mirrors
got out of step. I want to write a checker that can be used on a
running system, and would like to know if there is enough commonality
in implementations to extend this to RAID (yes, I know that mirroring
is also called RAID-1, but it predates RAID by a long way).

For example, N-way parity can be done as simple XOR, but the result
can be 0 or 1.

Also, a lot of vendors support 5+2 RAID, which implies a more complex
checksum calculation, but it isn't clear what.

Regards,
Nick Maclaren.

lewy

2004-08-10, 3:47 am

Nick

May be of some use to you, Search on the web for a guy called "John Wakerly ", I would post you some exact URL's but are short on time. The guys a Proff so will have somewhere the exact equation.

Good luck.

Lewy