linux-lvm.redhat.com archive mirror
 help / color / mirror / Atom feed
From: Phillip Susi <phill@thesusis.net>
To: LVM general discussion and development <linux-lvm@redhat.com>
Cc: "Tomas Dalebjörk" <tomas.dalebjork@gmail.com>
Subject: Re: [linux-lvm] how to convert a disk containing a snapshot to a snapshot lv?
Date: Mon, 20 Dec 2021 09:51:45 -0500	[thread overview]
Message-ID: <87v8zj1g7h.fsf@vps.thesusis.net> (raw)
In-Reply-To: <CACrcyf+2uz_ngeVdq48WjSg6ZaarRpVXs8TZwzpQ4hnW7D7xGg@mail.gmail.com>


I'm confused.  What exactly are you trying to do here?  I can't think of
any reason why you would want to copy a snapshot lv to a file then try
to loop mount it.

Tomas Dalebjörk <tomas.dalebjork@gmail.com> writes:

> Hi,
>
> I am trying to understand how to convert a disk containing snapshot data.
> This is how I tested this:
> 1. locate the snapshot testlv.211218.232255
> root@debian10:/dev/mapper# lvs
>   LV                   VG          Attr       LSize   Pool Origin Data%
>  Meta%  Move Log Cpy%Sync Convert
>   home                 debian10-vg -wi-ao----   1.00g
>   root                 debian10-vg -wi-ao----  <3.81g
>   swap_1               debian10-vg -wi-ao---- 976.00m
>   testlv               debian10-vg owi-aos--- 100.00m
>   testlv.211218.232255 debian10-vg swi-a-s--- 104.00m      testlv 1.44
> root@debian10:/dev/mapper#
>
> 2. copy the lv - cow data to a file
> # dd if=/dev/mapper/debian10--vg-testlv.211218.232255-cow of=/tmp/out
> bs=1024
>
> 3. Setup a loopback disk for the file
> # losetup -fP /tmp/out
>
> 4. Verify that disk exists
> root@debian10:/dev/mapper# losetup -a
> /dev/loop0: [65025]:39274 (/tmp/out)
> root@debian10:/dev/mapper#
>
> 5. Try converting the disk using lvconvert command
> # lvconvert -Zn -s debian10-vg/testlv /tmp/out
>   "/tmp/out": Invalid path for Logical Volume.
>
> 6. Trying creating a softlink in /dev/mapper
> # ln -s /tmp/out debian10--vg-loopback
>
> 7. verify link
> root@debian10:/dev/mapper# ls -la
> total 0
> drwxr-xr-x  2 root root     240 Dec 19 17:40 .
> drwxr-xr-x 18 root root    3820 Dec 19 17:22 ..
> crw-------  1 root root 10, 236 Dec 10 19:10 control
> lrwxrwxrwx  1 root root       7 Dec 10 19:10 debian10--vg-home -> ../dm-5
> lrwxrwxrwx  1 root root       8 Dec 19 17:40 debian10--vg-loopback ->
> /tmp/out
> lrwxrwxrwx  1 root root       7 Dec 13 22:20 debian10--vg-root -> ../dm-1
> lrwxrwxrwx  1 root root       7 Dec 10 19:10 debian10--vg-swap_1 -> ../dm-4
> lrwxrwxrwx  1 root root       7 Dec 18 23:23 debian10--vg-testlv -> ../dm-0
> lrwxrwxrwx  1 root root       7 Dec 18 23:23
> debian10--vg-testlv.211218.232255 -> ../dm-6
> lrwxrwxrwx  1 root root       7 Dec 18 23:23
> debian10--vg-testlv.211218.232255-cow -> ../dm-3
> lrwxrwxrwx  1 root root       7 Dec 18 23:23 debian10--vg-testlv-real ->
> ../dm-2
> root@debian10:/dev/mapper#
>
> 8. retrying lvconvert command
> root@debian10:/dev/mapper# lvconvert -Zn -s debian10-vg/testlv
> /dev/mapper/debian10--vg-loopback
>   Failed to find logical volume "debian10-vg/loopback"
> root@debian10:/dev/mapper#
>
> Are there more things to be considered, such as recreating pv data on disk?
>
> Regards Tomas
> _______________________________________________
> 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/

  reply	other threads:[~2021-12-20 15:02 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-19 16:43 Tomas Dalebjörk
2021-12-20 14:51 ` Phillip Susi [this message]
2021-12-21 13:46 ` Zdenek Kabelac
2021-12-21 14:44   ` Tomas Dalebjörk
2021-12-21 15:30     ` Zdenek Kabelac
2021-12-21 16:12       ` Tomas Dalebjörk
2021-12-22 10:40         ` Zdenek Kabelac
2021-12-28  5:04         ` Stuart D Gathman
2021-12-28  6:40           ` Tomas Dalebjörk
2021-12-29 13:35             ` Stuart D Gathman
2021-12-21 19:23     ` Phillip Susi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=87v8zj1g7h.fsf@vps.thesusis.net \
    --to=phill@thesusis.net \
    --cc=linux-lvm@redhat.com \
    --cc=tomas.dalebjork@gmail.com \
    --subject='Re: [linux-lvm] how to convert a disk containing a snapshot to a snapshot lv?' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).