Re: [linux-lvm] Replace Drive in RAID6

[Heinz Mauelshagen <heinzm@redhat.com>]

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On Mon, Nov 8, 2021 at 8:08 AM Adam Puleo <adam.puleo@icloud.com> wrote:

> Hello Everyone,
>

Hi,
for starters, which kernel/distro is this?

Also, all layout changes on RaidLVs require activated ones.



>
> Since the sub-LV #0 has errored, LVM will not let me activate the logical
> volume.
>
> Is there a way to remap the #0 sub-LV to the replaced disk or resizing the
> RAID6 to one less disk?
>

Each of the RAID6 SubLV pairs has an internal id and all data and parity
(P+Q syndromes) have been stored in a rotating pattern  >  no to the
remapping part.

Also no to the resize, as it'd need a fully operational radi6, thus
repairing the RaidLV is needed.

As mentioned, '"lvchange --rebuild ..." is inadequate to repair RaidLVs
with broken/lost PVs, "lvchange --repair $RaidLV" is.

In order to diagnose why your raid6 LV now fails to activate via "lvchange
-ay --activationmode degraded $RaidLV" which is the proper way to go about
it,
can you please describe any/all updating steps you took after the drive
failed rendering your raid6 LV degraded?  Please don't change anything
until you made
that transparent so that we keep chances to fix this...

FYI:
"lvconvert --(repair|replace) ..." difference is the former repairing
RaidLVs with failed PVs by allocating space on different, accessible PVs
hence causing the RaidLV to become fully operational after rebuilding all
missing block content by using parity stored on the remaining rimage SubLVs
vs. the latter allowing to replace mappings to intact PVs by remapping the
RAID SubLV pair to different ones (e.g. faster or less contended PVs).

Thanks,
Heinz



>
> Thank you,
> -Adam
>
>
> On Nov 4, 2021, at 7:21 PM, Adam Puleo <adam.puleo@icloud.com> wrote:
>
> Hello Andreas,
>
> After deactivating each of the individual rmage and rmeta volumes I
> receive this error:
> # lvchange -a y --activationmode degraded vg_data/lv_data
>  device-mapper: reload ioctl on  (253:12) failed: Invalid argument
>
> In messages I see the following errors:
> Nov  4 19:19:43 nas kernel: device-mapper: raid: Failed to read superblock
> of device at position 0
> Nov  4 19:19:43 nas kernel: device-mapper: raid: New device injected into
> existing raid set without 'delta_disks' or 'rebuild' parameter specified
> Nov  4 19:19:43 nas kernel: device-mapper: table: 253:12: raid: Unable to
> assemble array: Invalid superblocks
> Nov  4 19:19:43 nas kernel: device-mapper: ioctl: error adding target to
> table
>
> Am I not adding the new drive to the RAID correctly? I first did a
> pvcreate and then a vgextend.
>
> I was using the —rebuild option because I know which physical drive is
> bad. In the lvmraid man page it says —repair might not know which is the
> correct block to use so to use —rebuild.
>
> Thank you,
> -Adam
>
>
>
> On Nov 3, 2021, at 7:25 AM, Andreas Schrägle <linux-lvm@ajs124.de> wrote:
>
> On Tue, 2 Nov 2021 22:56:18 -0700
> Adam Puleo <adam.puleo@icloud.com> wrote:
>
> > Hello,
> >
> > One of my drives failed in my RAID6 and I’m trying to replace it without
> success.
> >
> > I’m trying to rebuild the failed drive (/dev/sda): lvchange --rebuild
> /dev/sda vg_data
> >
> > But I’m receiving the error: vg_data/lv_data must be active to perform
> this operation.
> >
> > I have tried to activate the logical volume without success.
> >
> > How do I go about activating the volume so that I can rebuild the failed
> drive?
> >
> > Thanks,
> > -Adam
> >
> > # lvs -a -o name,segtype,devices
> > LV                       Type   Devices
>
> > lv_data                  raid6
> lv_data_rimage_0(0),lv_data_rimage_1(0),lv_data_rimage_2(0),lv_data_rimage_3(0),lv_data_rimage_4(0)
> > [lv_data_rimage_0]       error
>
> > [lv_data_rimage_1]       linear /dev/sdc1(1)
>
> > [lv_data_rimage_2]       linear /dev/sdb1(1)
>
> > [lv_data_rimage_3]       linear /dev/sdf1(1)
>
> > [lv_data_rimage_4]       linear /dev/sde1(2)
>
> > [lv_data_rmeta_0]        error
>
> > [lv_data_rmeta_1]        linear /dev/sdc1(0)
>
> > [lv_data_rmeta_2]        linear /dev/sdb1(0)
>
> > [lv_data_rmeta_3]        linear /dev/sdf1(0)
>
> > [lv_data_rmeta_4]        linear /dev/sde1(0)
>
> >
> > # lvs -a
> > LV                       VG            Attr       LSize   Pool Origin
> Data%  Meta%  Move Log Cpy%Sync Convert
> > lv_data                  vg_data       rwi---r--- 990.00g
>
> > [lv_data_rimage_0]       vg_data       vwi-a-r-r- 330.00g
>
> > [lv_data_rimage_1]       vg_data       Iwi-a-r-r- 330.00g
>
> > [lv_data_rimage_2]       vg_data       Iwi-a-r-r- 330.00g
>
> > [lv_data_rimage_3]       vg_data       Iwi-a-r-r- 330.00g
>
> > [lv_data_rimage_4]       vg_data       Iwi-a-r-r- 330.00g
>
> > [lv_data_rmeta_0]        vg_data       ewi-a-r-r-   4.00m
>
> > [lv_data_rmeta_1]        vg_data       ewi-a-r-r-   4.00m
>
> > [lv_data_rmeta_2]        vg_data       ewi-a-r-r-   4.00m
>
> > [lv_data_rmeta_3]        vg_data       ewi-a-r-r-   4.00m
>
> > [lv_data_rmeta_4]        vg_data       ewi-a-r-r-   4.00m
>
> >
> >
> >
> > _______________________________________________
> > linux-lvm mailing list
> > linux-lvm@redhat.com
> > https://listman.redhat.com/mailman/listinfo/linux-lvm
> > read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
> Hello Adam,
>
> how exactly have you tried to activate the LV so far?
>
> lvchange with --activationmode degraded should work, no?
>
> Also, are you sure that --rebuild is the correct operation?
>
> man 7 lvmraid suggest you might want --repair or --replace instead.
>
> Best Regards
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/
>
>
> _______________________________________________
> linux-lvm mailing list
> linux-lvm@redhat.com
> https://listman.redhat.com/mailman/listinfo/linux-lvm
> read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

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