On 09/20/2013 10:56 AM, Francis Moreau wrote: > Hello Martin, > > On Mon, Sep 16, 2013 at 7:04 PM, Martin Wilck <mwilck@xxxxxxxx> wrote: >> On 09/16/2013 03:56 PM, Francis Moreau wrote: >> >>> I did give your patch "DDF: compare_super_ddf: fix sequence number >>> check" a try and now mdadm is able to detect a difference between the >>> 2 disks. Therefore it refuses to insert the second disk which is >>> better. >>> >>> However it's still not able to detect which version is the "fresher" >>> like mdadm does with soft RAID1 (metadata 1.2). Therefore mdadm is not >>> able to kick out the first disk if it's the outdated one. >>> >>> Is that expected ? >> >> At the moment, yes. This needs work. >> > > Actually this is worse than I thought: with your patch applied mdadm > refuses to add back a spare disk into a degraded DDF array. > > For example on a DDF array: > > # cat /proc/mdstat > Personalities : [raid1] > md126 : active raid1 sdb[1] sda[0] > 2064384 blocks super external:/md127/0 [2/2] [UU] > > md127 : inactive sdb[1](S) sda[0](S) > 65536 blocks super external:ddf > > unused devices: <none> > > # mdadm /dev/md126 --fail sdb > [ 24.118434] md/raid1:md126: Disk failure on sdb, disabling device. > [ 24.118437] md/raid1:md126: Operation continuing on 1 devices. > mdadm: set sdb faulty in /dev/md126 > > # mdadm /dev/md127 --remove sdb > mdadm: hot removed sdb from /dev/md127 > > # mdadm /dev/md127 --add /dev/sdb > mdadm: added /dev/sdb > > # cat /proc/mdstat > Personalities : [raid1] > md126 : active raid1 sda[0] > 2064384 blocks super external:/md127/0 [2/1] [U_] > > md127 : inactive sdb[1](S) sda[0](S) > 65536 blocks super external:ddf > > unused devices: <none> > > > As you can see the reinserted disk sdb sits as spare and isn't added > back to the array. That's correct. You marked that disk failed. > Is it possible to add this major feature work again and keep your improvement ? No. A failed disk can't be added again without rebuild. I am positive about that. Martin > > Thanks -- 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
