On Mon, Dec 15, 2008 at 6:54 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > On Mon, Dec 15, 2008 at 2:09 PM, Neil Brown <neilb@xxxxxxx> wrote: >> On Monday December 15, jnelson-linux-raid@xxxxxxxxxxx wrote: >>> I have a software raid1 which underwent a recovery recently. >>> While it was recovering, I could not understand why I was seeing an >>> equal amount of *read* I/O as write I/O to the device the raid1 was >>> recovering to. That's to say, the raid1 was rebuilding on to a spare >>> but instead of just writing I was seeing (nearly exactly) the same >>> amount of read I/O as write I/O. The non-spare device was getting >>> almost exclusively read I/O as expected. Why was the spare getting any >>> read I/O at all? .. > Yes it is hard to guess what is happening here; however, should not > the following commit go to -stable? > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=56ac36d722d0d27c03599d1245ac0ab59e474e5c Is it possible this commit is (partially) responsible for what I was seeing? Under what conditions would it trigger? For me, it was a thoroughly unexpected recovery - I had expected to --re-add the device and have it resync up very quickly - this normally takes a few seconds, but instead for some reason it went into a full recovery. I was stracing the nbd-server process responsible for the block device and it was definitely getting read and write requests in equal measure. However, later when I actually did rebuild the array the recovery was (almost) 100% write. -- Jon -- 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
