On Fri, Sep 20, 2013 at 11:08 PM, Francis Moreau <francis.moro@xxxxxxxxx> wrote: > Hello Martin, > > On Fri, Sep 20, 2013 at 8:07 PM, Martin Wilck <mwilck@xxxxxxxx> wrote: >> 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 able to kick out the first disk if it's the outdated one.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. >> > > Hmm that's not the case with soft linux RAID AFAICS: doing the same > thing with soft RAID and the reinserted disk is added to the raid > array and it's synchronised automatically. You can try it easily. BTW, that's also the case for DDF if I don't apply your patch. > > Could you show me the mdadm command I should use to insert sdb into the array ? > > Thanks. > -- > Francis -- Francis -- 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
