[linux-lvm] Unsync-ed LVM Mirror

Discussion:

Liwei

2018-02-03 09:43:05 UTC

Hi list,
I had a LV that I was converting from linear to mirrored (not
raid1) whose source device failed partway-through during the initial
sync.

I've since recovered the source device, but it seems like the
mirror is still acting as if some blocks are not readable? I'm getting
this in my logs, and the FS is full of errors:

[ +1.613126] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.000278] device-mapper: raid1: Primary mirror (253:25) failed
while out-of-sync: Reads may fail.
[ +0.085916] device-mapper: raid1: Mirror read failed.
[ +0.196562] device-mapper: raid1: Mirror read failed.
[ +0.000237] Buffer I/O error on dev dm-27, logical block 5371800560,
async page read
[ +0.592135] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.082882] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.246945] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.107374] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.083344] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.114949] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.085056] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.203929] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.157953] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +3.065247] recovery_complete: 23 callbacks suppressed
[ +0.000001] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.128064] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.103100] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.107827] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.140871] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.132844] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.124698] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.138502] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.117827] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.125705] device-mapper: raid1: Unable to read primary mirror
during recovery
[Feb 3 17:09] device-mapper: raid1: Mirror read failed.
[ +0.167553] device-mapper: raid1: Mirror read failed.
[ +0.000268] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
[ +0.135138] device-mapper: raid1: Mirror read failed.
[ +0.000238] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
[ +0.000365] device-mapper: raid1: Mirror read failed.
[ +0.000315] device-mapper: raid1: Mirror read failed.
[ +0.000213] Buffer I/O error on dev dm-27, logical block 5367896888,
async page read
[ +0.000276] device-mapper: raid1: Mirror read failed.
[ +0.000199] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read

However, if I take down the destination device and restart the LV
with --activateoption partial, I can read my data and everything
checks out.

My theory (and what I observed) is that lvm continued the initial
sync even after the source drive stopped responding, and has now
mapped the blocks that it 'synced' as dead. How can I make lvm retry
those blocks again?

In fact, I don't trust the mirror anymore, is there a way I can
conduct a scrub of the mirror after the initial sync is done? I read
about --syncaction check, but seems like it only notes the number of
inconsistencies. Can I have lvm re-mirror the inconsistencies from the
source to destination device? I trust the source device because we ran
a btrfs scrub on it and it reported that all checksums are valid.

It took months for the mirror sync to get to this stage (actually,
why does it take months to mirror 20TB?), I don't want to start it all
over again.

Warm regards,
Liwei

Liwei

2018-02-05 03:21:49 UTC

Permalink

Post by Liwei
Hi list,
I had a LV that I was converting from linear to mirrored (not
raid1) whose source device failed partway-through during the initial
sync.
I've since recovered the source device, but it seems like the
mirror is still acting as if some blocks are not readable? I'm getting
[ +1.613126] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.000278] device-mapper: raid1: Primary mirror (253:25) failed
while out-of-sync: Reads may fail.
[ +0.085916] device-mapper: raid1: Mirror read failed.
[ +0.196562] device-mapper: raid1: Mirror read failed.
[ +0.000237] Buffer I/O error on dev dm-27, logical block 5371800560,
async page read
[ +0.592135] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.082882] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.246945] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.107374] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.083344] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.114949] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.085056] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.203929] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.157953] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +3.065247] recovery_complete: 23 callbacks suppressed
[ +0.000001] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.128064] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.103100] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.107827] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.140871] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.132844] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.124698] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.138502] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.117827] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.125705] device-mapper: raid1: Unable to read primary mirror
during recovery
[Feb 3 17:09] device-mapper: raid1: Mirror read failed.
[ +0.167553] device-mapper: raid1: Mirror read failed.
[ +0.000268] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
[ +0.135138] device-mapper: raid1: Mirror read failed.
[ +0.000238] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
[ +0.000365] device-mapper: raid1: Mirror read failed.
[ +0.000315] device-mapper: raid1: Mirror read failed.
[ +0.000213] Buffer I/O error on dev dm-27, logical block 5367896888,
async page read
[ +0.000276] device-mapper: raid1: Mirror read failed.
[ +0.000199] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
However, if I take down the destination device and restart the LV
with --activateoption partial, I can read my data and everything
checks out.
My theory (and what I observed) is that lvm continued the initial
sync even after the source drive stopped responding, and has now
mapped the blocks that it 'synced' as dead. How can I make lvm retry
those blocks again?
In fact, I don't trust the mirror anymore, is there a way I can
conduct a scrub of the mirror after the initial sync is done? I read
about --syncaction check, but seems like it only notes the number of
inconsistencies. Can I have lvm re-mirror the inconsistencies from the
source to destination device? I trust the source device because we ran
a btrfs scrub on it and it reported that all checksums are valid.
It took months for the mirror sync to get to this stage (actually,
why does it take months to mirror 20TB?), I don't want to start it all
over again.
Warm regards,
Liwei

Okay, the sync managed to reach 99.99%, and now there's no drive
activity, it is just stuck there. What should I do? Theoretically, if
I can take a look at the contents of mlog and manipulate it, I can
manually do a sync of the failed segments, and remove lvm's opinion of
them being missing.

I'm looking through the lvm2 source for the format but if someone can
point out the way (or a better way), I'll be very appreciative!

Also, is there a way I can access the mlog and mimage* subvolumes directly?

Warm regards,
Liwei

Eric Ren

2018-02-05 07:27:09 UTC

Permalink

Hi,

Your LVM version and kernel version please?

like:
""""
# lvm version
LVM version: 2.02.177(2) (2017-12-18)
Library version: 1.03.01 (2017-12-18)
Driver version: 4.35.0

# uname -a
Linux sle15-c1-n1 4.12.14-9.1-default #1 SMP Fri Jan 19 09:13:51 UTC
2018 (849a2fe) x86_64 x86_64 x86_64 GNU/Linux
"""

Eric

Liwei

2018-02-05 09:26:08 UTC

Permalink

This is a long story. Precisely, I hit that bug (?), due to one half
of the mirror (the source) encountering bad sectors. So I was forced
to upgrade the kernel in order to salvage the situation (the bug was
so persistent, I could not get to a shell even in single-user mode -
had to boot a version of Ubuntu with the patch applied, chroot and
install the update).

I'm not versed enough with the inner workings of LVM to understand the
differences with what was accepted upstream and the 2 patches you
worked on (what is a bio?), so it didn't occur to me that I'd meet
with problems down the road.

I was using mirror because I was following this guide (which in
retrospect, was seriously outdated),
https://utcc.utoronto.ca/~cks/space/blog/linux/LVMCautiousMigration ,
and some reading made me think that it was not possible to cleanly
undo a mirror by raid1.

A little background: We were trying to (safely?) migrate our VG from
an antiquated 13x2TB raid6 array to a shiny new 6x6TB array while
minimizing downtime. So the plan was to turn on mirroring, wait for it
to sync, then split the mirror. Of course as with all poorly-planned
plans go, 2 of the source drives dropped out and a third drive
developed bad sectors, all within a few days. And here I am with this
problem.

Anyways, I'm still not sure what's happening, but is there an easy (in
terms of, do-not-need-to-resync-everything) way to proceed?

Warm regards,
Liwei

Months ago, I worked on a NULL pointer deference crash on dm mirror
target. I worked out two patches
to fix the crash issue, but when I was submitting them, I found that
upstream had "fixed" the crash by
- https://patchwork.kernel.org/patch/9808897/
"""

Which kernel version is this ?
https://bugzilla.redhat.com/show_bug.cgi?id=1382382
There similar BZ for md-raid based mirrors (--type raid1)
https://bugzilla.redhat.com/show_bug.cgi?id=1416099

"""
Revert "dm mirror: use all available legs on multiple failures"

Ohh - I've -rc6 - while this 'revert' patch went to 4.12-rc7.
I'm now starting to wonder why?
It's been a real fix for a real issue - and 'revert' message states
there is no such problem ??
I'm confused....
Mike - have you tried the sequence from BZ ?
Zdenek
"""
1. the crash issue do disappear;
2. the "reverting" fixing way is likely wrong, but I did follow up it
further because
people now mainly uses raid1 instead of mirror - my fault to think that
way.
But, I was just feeling it's hard to persuade the maintainer to revert the
"reverting fixes"
and try my fix.
Anyway, why are you using mirror? why not raid1?
Eric
Hi Eric,
# lvm version
LVM version: 2.02.176(2) (2017-11-03)
Library version: 1.02.145 (2017-11-03)
Driver version: 4.37.0
Configuration: ./configure --build=x86_64-linux-gnu --prefix=/usr
--includedir=${prefix}/include --mandir=${prefix}/share/man
--infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var
--disable-silent-rules --libdir=${prefix}/lib/x86_64-linux-gnu
--libexecdir=${prefix}/lib/x86_64-linux-gnu --runstatedir=/run
--disable-maintainer-mode --disable-dependency-tracking --exec-prefix=
--bindir=/bin --libdir=/lib/x86_64-linux-gnu --sbindir=/sbin
--with-usrlibdir=/usr/lib/x86_64-linux-gnu --with-optimisation=-O2
--with-cache=internal --with-clvmd=corosync --with-cluster=internal
--with-device-uid=0 --with-device-gid=6 --with-device-mode=0660
--with-default-pid-dir=/run --with-default-run-dir=/run/lvm
--with-default-locking-dir=/run/lock/lvm --with-thin=internal
--with-thin-check=/usr/sbin/thin_check --with-thin-dump=/usr/sbin/thin_dump
--with-thin-repair=/usr/sbin/thin_repair --enable-applib
--enable-blkid_wiping --enable-cmdlib --enable-cmirrord --enable-dmeventd
--enable-dbus-service --enable-lvmetad --enable-lvmlockd-dlm
--enable-lvmlockd-sanlock --enable-lvmpolld --enable-notify-dbus
--enable-pkgconfig --enable-readline --enable-udev_rules --enable-udev_sync
# uname -a
Linux dataserv 4.14.0-3-amd64 #1 SMP Debian 4.14.13-1 (2018-01-14) x86_64
GNU/Linux
Warm regards,
Liwei

Hi,
Your LVM version and kernel version please?
""""
# lvm version
LVM version: 2.02.177(2) (2017-12-18)
Library version: 1.03.01 (2017-12-18)
Driver version: 4.35.0
# uname -a
Linux sle15-c1-n1 4.12.14-9.1-default #1 SMP Fri Jan 19 09:13:51 UTC 2018
(849a2fe) x86_64 x86_64 x86_64 GNU/Linux
"""
Eric

Hi list,
I had a LV that I was converting from linear to mirrored (not
raid1) whose source device failed partway-through during the initial
sync.
I've since recovered the source device, but it seems like the
mirror is still acting as if some blocks are not readable? I'm getting
[ +1.613126] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.000278] device-mapper: raid1: Primary mirror (253:25) failed
while out-of-sync: Reads may fail.
[ +0.085916] device-mapper: raid1: Mirror read failed.
[ +0.196562] device-mapper: raid1: Mirror read failed.
[ +0.000237] Buffer I/O error on dev dm-27, logical block 5371800560,
async page read
[ +0.592135] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.082882] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.246945] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.107374] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.083344] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.114949] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.085056] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.203929] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.157953] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +3.065247] recovery_complete: 23 callbacks suppressed
[ +0.000001] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.128064] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.103100] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.107827] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.140871] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.132844] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.124698] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.138502] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.117827] device-mapper: raid1: Unable to read primary mirror
during recovery
[ +0.125705] device-mapper: raid1: Unable to read primary mirror
during recovery
[Feb 3 17:09] device-mapper: raid1: Mirror read failed.
[ +0.167553] device-mapper: raid1: Mirror read failed.
[ +0.000268] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
[ +0.135138] device-mapper: raid1: Mirror read failed.
[ +0.000238] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
[ +0.000365] device-mapper: raid1: Mirror read failed.
[ +0.000315] device-mapper: raid1: Mirror read failed.
[ +0.000213] Buffer I/O error on dev dm-27, logical block 5367896888,
async page read
[ +0.000276] device-mapper: raid1: Mirror read failed.
[ +0.000199] Buffer I/O error on dev dm-27, logical block 5367765816,
async page read
However, if I take down the destination device and restart the LV
with --activateoption partial, I can read my data and everything
checks out.
My theory (and what I observed) is that lvm continued the initial
sync even after the source drive stopped responding, and has now
mapped the blocks that it 'synced' as dead. How can I make lvm retry
those blocks again?
In fact, I don't trust the mirror anymore, is there a way I can
conduct a scrub of the mirror after the initial sync is done? I read
about --syncaction check, but seems like it only notes the number of
inconsistencies. Can I have lvm re-mirror the inconsistencies from the
source to destination device? I trust the source device because we ran
a btrfs scrub on it and it reported that all checksums are valid.
It took months for the mirror sync to get to this stage (actually,
why does it take months to mirror 20TB?), I don't want to start it all
over again.
Warm regards,
Liwei
_______________________________________________
linux-lvm mailing list
https://www.redhat.com/mailman/listinfo/linux-lvm
read the LVM HOW-TO at http://tldp.org/HOWTO/LVM-HOWTO/

Eric Ren

2018-02-05 10:07:20 UTC

Permalink

Hi,

Hi Eric,
# lvm version
Â LVM version:Â Â Â 2.02.176(2) (2017-11-03)
Â Library version: 1.02.145 (2017-11-03)
Â Driver version:Â 4.37.0
Â Configuration:Â Â ./configure --build=x86_64-linux-gnu --prefix=/usr
--includedir=${prefix}/include --mandir=${prefix}/share/man
--infodir=${prefix}/share/info --sysconfdir=/etc --localstatedir=/var
--disable-silent-rules --libdir=${prefix}/lib/x86_64-linux-gnu
--libexecdir=${prefix}/lib/x86_64-linux-gnu --runstatedir=/run
--disable-maintainer-mode --disable-dependency-tracking --exec-prefix=
--bindir=/bin --libdir=/lib/x86_64-linux-gnu --sbindir=/sbin
--with-usrlibdir=/usr/lib/x86_64-linux-gnu --with-optimisation=-O2
--with-cache=internal --with-clvmd=corosync --with-cluster=internal
--with-device-uid=0 --with-device-gid=6 --with-device-mode=0660
--with-default-pid-dir=/run --with-default-run-dir=/run/lvm
--with-default-locking-dir=/run/lock/lvm --with-thin=internal
--with-thin-check=/usr/sbin/thin_check
--with-thin-dump=/usr/sbin/thin_dump
--with-thin-repair=/usr/sbin/thin_repair --enable-applib
--enable-blkid_wiping --enable-cmdlib --enable-cmirrord
--enable-dmeventd --enable-dbus-service --enable-lvmetad
--enable-lvmlockd-dlm --enable-lvmlockd-sanlock --enable-lvmpolld
--enable-notify-dbus --enable-pkgconfig --enable-readline
--enable-udev_rules --enable-udev_sync
# uname -a
Linux dataserv 4.14.0-3-amd64 #1 SMP Debian 4.14.13-1 (2018-01-14)
x86_64 GNU/Linux

Sorry, I'm not sure if this the root cause of your issue, without
testing myself. If you have interest to
have a try, you can revert

cd15fb64ee56192760ad5c1e2ad97a65e735b18b (Revert "dm mirror: use all
available legs on multiple failures")

and try my patch in https://patchwork.kernel.org/patch/9808897/

The "reverting" fix for the crash issue is in 4.14.0 kernel.
'""
ââ***@ws ~/workspace/linuxÂ â¹masterâº
â°â$ git log --grep "Revert \"dm mirror: use all available legs on
multiple failures\""

commit cd15fb64ee56192760ad5c1e2ad97a65e735b18b
Author: Mike Snitzer <***@redhat.com>
Date:Â Â Thu Jun 15 08:39:15 2017 -0400

Â Â Â Revert "dm mirror: use all available legs on multiple failures"

Â Â Â This reverts commit 12a7cf5ba6c776a2621d8972c7d42e8d3d959d20.

ââ***@ws ~/workspace/linuxÂ â¹masterâº
â°â$ git describe cd15fb64ee56192760ad5c1e2ad97a65e735b18b
v4.12-rc5-2-gcd15fb64ee56
"""

Eric

Warm regards,
Liwei
Hi,
Your LVM version and kernel version please?
""""
# lvm version
Â LVM version:Â Â Â Â 2.02.177(2) (2017-12-18)
Â Library version: 1.03.01 (2017-12-18)
Â Driver version:Â 4.35.0
# uname -a
Linux sle15-c1-n1 4.12.14-9.1-default #1 SMP Fri Jan 19 09:13:51
UTC 2018 (849a2fe) x86_64 x86_64 x86_64 GNU/Linux
"""
Eric
Hi list,
Â Â Â I had a LV that I was converting from linear to mirrored (not
raid1) whose source device failed partway-through during the initial
sync.
Â Â Â I've since recovered the source device, but it seems like the
mirror is still acting as if some blocks are not readable? I'm getting
[Â +1.613126] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.000278] device-mapper: raid1: Primary mirror (253:25) failed
while out-of-sync: Reads may fail.
[Â +0.085916] device-mapper: raid1: Mirror read failed.
[Â +0.196562] device-mapper: raid1: Mirror read failed.
[Â +0.000237] Buffer I/O error on dev dm-27, logical block
5371800560,
async page read
[Â +0.592135] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.082882] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.246945] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.107374] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.083344] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.114949] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.085056] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.203929] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.157953] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +3.065247] recovery_complete: 23 callbacks suppressed
[Â +0.000001] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.128064] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.103100] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.107827] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.140871] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.132844] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.124698] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.138502] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.117827] device-mapper: raid1: Unable to read primary mirror
during recovery
[Â +0.125705] device-mapper: raid1: Unable to read primary mirror
during recovery
[Feb 3 17:09] device-mapper: raid1: Mirror read failed.
[Â +0.167553] device-mapper: raid1: Mirror read failed.
[Â +0.000268] Buffer I/O error on dev dm-27, logical block
5367765816,
async page read
[Â +0.135138] device-mapper: raid1: Mirror read failed.
[Â +0.000238] Buffer I/O error on dev dm-27, logical block
5367765816,
async page read
[Â +0.000365] device-mapper: raid1: Mirror read failed.
[Â +0.000315] device-mapper: raid1: Mirror read failed.
[Â +0.000213] Buffer I/O error on dev dm-27, logical block
5367896888,
async page read
[Â +0.000276] device-mapper: raid1: Mirror read failed.
[Â +0.000199] Buffer I/O error on dev dm-27, logical block
5367765816,
async page read
Â Â Â However, if I take down the destination device and
restart the LV
with --activateoption partial, I can read my data and everything
checks out.
Â Â Â My theory (and what I observed) is that lvm continued the
initial
sync even after the source drive stopped responding, and has now
mapped the blocks that it 'synced' as dead. How can I make lvm retry
those blocks again?
Â Â Â In fact, I don't trust the mirror anymore, is there a way
I can
conduct a scrub of the mirror after the initial sync is done? I read
about --syncaction check, but seems like it only notes the number of
inconsistencies. Can I have lvm re-mirror the inconsistencies from the
source to destination device? I trust the source device because we ran
a btrfs scrub on it and it reported that all checksums are valid.
Â Â Â It took months for the mirror sync to get to this stage
(actually,
why does it take months to mirror 20TB?), I don't want to start it all
over again.
Warm regards,
Liwei
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linux-lvm mailing list
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