On Mon, May 01, 2006 at 01:17:42AM +0200, Dick Snippe wrote: > Suppose a read action on a disk which is member of a raid5 (or raid1 or any > other raid where there's data redundancy) fails. > What ahppens next is that the entire disk is marked as "failed" and a raid5 > rebuild is initiated. > > However, that seems like overkill to me. If only one sector on one disk > failed, that sector could be re-calculated (using parity calculations) > AND written back to the original disk (i.e. the disk with the bad sector). > Any modern disk will do sector remapping, so the bad sector will simply be > replaced by a good one and there's no need to fail the entire disk. Sigh. Just checked the kernel source. Recent 2.6 kernels (>= 2.6.15) appear to have support for this (See raid5_end_read_request in drivers/md/raid5.c). Earlier versions don't. -- Dick Snippe - Publieke Omroep Internet Services Gebouw 12.401 (peperbus) Sumatralaan 45 Hilversum \ fight war tel +31 35 6774252, email beheer@xxxxxxxxx []() \ not wars - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
