From: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>
To: Zdenek Kabelac <zkabelac@redhat.com>
Cc: LVM general discussion and development <linux-lvm@redhat.com>
Subject: Re: [linux-lvm] exposing snapshot block device
Date: Mon, 7 Sep 2020 21:56:07 +0200 [thread overview]
Message-ID: <99376C3F-DB70-4917-BA62-3A51A55F6DF5@gmail.com> (raw)
In-Reply-To: <4081c11e-d2b0-ebfa-d1a0-92a4efc79e81@redhat.com>
hi
I tried all these steps
but when I associated the snapshot cow device back to an empty origin, and typed the lvs command
the data% output shows 0% instead of 37% ?
so it looks like that the lvconvert -s vg1/lvsnap vg1/lv0 looses the cow data?
perhaps ypu can guide me how this can be done?
btw, just to emulate s full copy, I executed the
dd if=/dev/vg0/lv0 of=/dev/vg1/lv0
before the lvconvert -s, to make sure the last data is there
and than I tried to mount the vg1/lv0 which worked fine
but the data was not at snapshot view
even mounting vg1/lvsnap works fine
but with wrong data
confused over how and why vgmerge should be used as vgsplit does the work?
regards Tomas
Sent from my iPhone
> On 7 Sep 2020, at 18:42, Zdenek Kabelac <zkabelac@redhat.com> wrote:
>
> Dne 07. 09. 20 v 18:34 Tomas Dalebjörk napsal(a):
>> thanks for feedback
>> so if I understand this correctly
>> # fallocate -l 100M /tmp/pv1
>> # fallocate -l 100M /tmp/pv2
>> # fallocate -l 100M /tmp/pv3
>> # losetup —find —show /tmp/pv1
>> # losetup —find —show /tmp/pv2
>> # losetup —find —show /tmp/pv3
>> # vgcreate vg0 /dev/loop0
>> # lvcreate -n lv0 -l 1 vg0
>> # vgextend vg0 /dev/loop1
>> # lvcreate -s -l 1 -n lvsnap /dev/loop1
>> # vgchange -a n vg0
>> # lvconvert —splitsnapshot vg0/lvsnap
>> # vgreduce vg0 /dev/loop1
>
>
> Hi
>
> Here you would need to use 'vgsplit' rather - otherwise you
> loose the mapping for whatever was living on /dev/loop1
>
>> # vgcreate vg1 /dev/loop2
>> # lvcreate -n lv0 -l 1 vg1
>> # vgextend vg1 /dev/loop1
>
> And 'vgmerge'
>
>
>> # lvconvert -s vg1/lvsnap vg1/lv0
>> not sure if the steps are correct?
>
>
> I hope you realize the content of vg1/lv0 must be exactly same
> as vg0/lv0.
>
> As snapshot COW volume contains only 'diff chunks' - so if you
> would attach snapshot to 'different' lv - you would get only mess.
>
>
> Zdenek
>
next prev parent reply other threads:[~2020-09-07 19:56 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-22 10:47 [linux-lvm] exposing snapshot block device Dalebjörk, Tomas
2019-10-22 13:57 ` Zdenek Kabelac
2019-10-22 15:29 ` Dalebjörk, Tomas
2019-10-22 15:36 ` Zdenek Kabelac
2019-10-22 16:13 ` Dalebjörk, Tomas
2019-10-23 10:26 ` Zdenek Kabelac
2019-10-23 10:56 ` Tomas Dalebjörk
2019-10-22 16:15 ` Stuart D. Gathman
2019-10-22 17:02 ` Tomas Dalebjörk
2019-10-22 21:38 ` Gionatan Danti
2019-10-22 22:53 ` Stuart D. Gathman
2019-10-23 6:58 ` Gionatan Danti
2019-10-23 10:06 ` Tomas Dalebjörk
2019-10-23 10:12 ` Zdenek Kabelac
2019-10-23 10:46 ` Zdenek Kabelac
2019-10-23 11:08 ` Gionatan Danti
2019-10-23 11:24 ` Tomas Dalebjörk
2019-10-23 11:26 ` Tomas Dalebjörk
2019-10-24 16:01 ` Zdenek Kabelac
2019-10-25 16:31 ` Tomas Dalebjörk
2019-11-04 5:54 ` Tomas Dalebjörk
2019-11-04 10:07 ` Zdenek Kabelac
2019-11-04 14:40 ` Tomas Dalebjörk
2019-11-04 15:04 ` Zdenek Kabelac
2019-11-04 17:28 ` Tomas Dalebjörk
2019-11-05 16:24 ` Zdenek Kabelac
2019-11-05 16:40 ` Mikulas Patocka
2019-11-05 20:56 ` Tomas Dalebjörk
2019-11-06 9:22 ` Zdenek Kabelac
2019-11-07 16:54 ` Mikulas Patocka
2019-11-07 17:29 ` Tomas Dalebjörk
2020-09-04 12:09 ` Tomas Dalebjörk
2020-09-04 12:37 ` Zdenek Kabelac
2020-09-07 13:09 ` Mikulas Patocka
2020-09-07 14:14 ` Dalebjörk, Tomas
2020-09-07 14:17 ` Zdenek Kabelac
2020-09-07 16:34 ` Tomas Dalebjörk
2020-09-07 16:42 ` Zdenek Kabelac
2020-09-07 17:37 ` Tomas Dalebjörk
2020-09-07 17:50 ` Zdenek Kabelac
2020-09-08 12:32 ` Dalebjörk, Tomas
2020-09-07 19:56 ` Tomas Dalebjörk [this message]
2020-09-07 20:22 ` Tomas Dalebjörk
2020-09-07 21:02 ` Tomas Dalebjörk
2019-10-23 12:12 ` Ilia Zykov
2019-10-23 12:20 ` Ilia Zykov
2019-10-23 13:05 ` Zdenek Kabelac
2019-10-23 14:40 ` Gionatan Danti
2019-10-23 15:46 ` Ilia Zykov
2019-10-23 12:59 ` Zdenek Kabelac
2019-10-23 14:37 ` Gionatan Danti
2019-10-23 15:37 ` Zdenek Kabelac
2019-10-23 17:16 ` Gionatan Danti
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