On Sat, 11 Sep 2010 00:58:21 -0400 Mike Hartman <mike@xxxxxxxxxxxxxxxxxxxx> wrote: > > If you add a bitmap (mdadm --grow /dev/md0 --bitmap=internal) after the > > current resync finished, then any subsequent resync due to an unclean > > shutdown will be much faster. > > I read somewhere (I think in the wiki) that an intent bitmap only > works properly on ext2 and ext3 and can cause trouble on other file > systems. Can I use one on ext4 (what I'm using)? I'm hoping/assuming > what I read just predates the common use of ext4. That is completely wrong. An intent bitmap works properly no matter what filesystem is on top. It does impose a small performance penalty for writes which is very work-load-dependant, and it is not impossible that different filesystems would suffer more or less from this, but I doubt you would notice. If you can find it again let me know and I'll try to get it fixed. > > Will I need to remove the bitmap before adding another disk and > growing the array to use it? If I don't, will it speed up that > operation any? You, you will need to remove the bitmap before growing the array. I really should fix that but it doesn't seem to rise to the top of my to-do list... And no, a bitmap would have no effect on a reshape operation even if it were allowed to be present. NeilBrown -- 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
