Il dom, 2003-10-26 alle 17:16, maarten van den Berg ha scritto: > Raid1 being a mirror set it does not make sense to > interleave anything. Either disk1 reads it first or disk2 reads it first. > Once you get the data from either disk, then you're done; no need to wait for > the second disk (giving you the identical datablock). OK I have some difficulties to explain it, I will try again: usually linux do read prefetch so when you read block "n" after it linux reads block "n+1". So the "n+1" block can be read at the same time on the other disk. Reading past mailing lists posts it seems that raid1 behaviour is this: 1) disk idle 2) request for block "n" 3) request is passed to hard disk with head nearer to block "n" (is it true? I am not sure) 4) request to block "n+1" "n+2" etc. are on the same disk so THE OTHER DISK IS READY FOR A READ REQUEST FROM OTHER PROCESSES 5) if sequential reading continue after some minutes the other disk is chosen to not stress too much only one disk (is it true?) Obviously this behaviour (point 4) helps servers with a lot of multitasking and processes. I prefer a "sequential" optimization. Can it be done? Thanks again! - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
