Thanks Neil that clarifies the situation. -----Original Message----- From: NeilBrown [mailto:neilb@xxxxxxx] Sent: 08 May 2009 01:32 To: Simon Jackson Cc: linux-raid@xxxxxxxxxxxxxxx Subject: Re: RAID 1 resync with both members good. On Thu, May 7, 2009 6:08 pm, Simon Jackson wrote: > Could someone help me understand why I am seeing the following > behaviour? > > We use a pair of disks with 3 RAID1 partitions inside an appliance > system. > > During testing we have seen some instances of the RAID devices resyncing > even though both members are marked as good in the output of > /proc/mdstat. That is exactly as expectedc. If one of the devices had failed and was being replaced by a spare, you would see "recovery" not "resync". Resync happens after an unclean shutdown. In that case, both drives have good data, but they might not be the same. The resync makes sure that all copies have exactly the same data. So you there must have been an unclean shutdown before the most recent restart. NeilBrown > > merc:~# cat /proc/mdstat > Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] > [raid4] [raid10] > md2 : active raid1 sda3[0] sdb3[1] > 7823552 blocks [2/2] [UU] > resync=DELAYED > md0 : active raid1 sda5[0] sdb5[1] > 7823552 blocks [2/2] [UU] > md1 : active raid1 sda6[0] sdb6[1] > 55841792 blocks [2/2] [UU] > [=================>...] resync = 88.8% (49606848/55841792) finish=8.4min > speed=12256K/sec > unused devices: <none> > > > Why would a resync occur if both members are marked us good? > > What we usually see when a drive is failed removed and readded is that > the resync marks the new drive as down "_" until the resync completes. > > Firstly why is a resync occurring when both drives are still good in the > raid set? Is this be expected behaviour or an indication of an > underlying problem. > > Thanks for any assistance. > > Using Debian 2.6.26-1 > > Thanks Simon. > -- > 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 > -- 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
