Robin Hill wrote: > On Sun Dec 01, 2013 at 10:07:07PM -0500, Wakko Warner wrote: > > > This is a general question, but I'll give a specific. > > > > If I create an array with assume clean and proceed to write to the device, > > what happens with the parity? > > > Doing that specifically should result in all parity being correct, yes. > Providing the writes are not going to a single disk in a stripe (in > which case read-modify-write may be used to update the parity rather > than a full stripe read and parity recalculation) then any write should > result in the parity for that stripe being written correctly. I think > RMW is only used in RAID5 currently though. I tested with raid6 as I mentioned in the command in the original mail. I ran a check and there were no mismatches. I also created a raid5 on the same amount of disks and tried again. I only wrote about 4gb and the mismatch count was 0 until it passed the 4gb mark. I was fairly certain that it would be correct, but I wanted to check. > Changing the stripe cache size won't affect the parity calculation at > all (except in terms of performance/throughput). I wasn't sure if that would make a difference or not. Doesn't hurt to ask. Thanks for the response. I must say that I've been a user of mdadm/linux software raid for some time now and I've only once lost an entire array. I appreciate seeing all the responses I've seen on the list over the years about how helpful everyone has been. -- Microsoft has beaten Volkswagen's world record. Volkswagen only created 22 million bugs. -- 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
