FAQ

[CentOS] LiveCD System recovery - Mounting LVM?

Johan Martinez
Jan 8, 2011 at 4:27 pm
Hi,

I am trying to recover data from my old system which had LVM. The disk had
two partitions - /dev/sda1 (boot, Linux) and /dev/sda2 (Linux LVM). I had
taken a backup of both partitions using dd.

Now I am booting of CentOS live cd for system restore. I recreated
partitions like previous system using fdisk and then used dd to dump all the
data onto it. I would like to mount sda2 as LVM, but I don't know how to do
that. Any steps or howto mount LVM manually would be really helpful. I think
I can recover the system once I am able to access sda1 and sda2. Any help?

jM.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.centos.org/pipermail/centos/attachments/20110108/b3c4386f/attachment.html
reply

Search Discussions

16 responses

  • Lamar Owen at Jan 8, 2011 at 4:50 pm

    On Saturday, January 08, 2011 04:27:39 pm Johan Martinez wrote:

    Now I am booting of CentOS live cd for system restore. I recreated
    partitions like previous system using fdisk and then used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I don't know how to do
    that. Any steps or howto mount LVM manually would be really helpful. I think
    I can recover the system once I am able to access sda1 and sda2. Any help?
    pvscan
    vgscan
    vgchange -ay
    lvscan

    (It has been awhile since I have done this; I know the vgchange -ay is required, but I don't recall if pvscan and lvscan were required or if I just used them for information....but I do think the vgscan was required.)

    In the lvscan output you should see the logical volumes; mount to the desired mountpoint with
    mount /dev/VOLUMEGROUP/LOGICALVOLUME MOUNTPOINT

    Or you can reboot the CentOS disk in rescue mode and have it find your system as part of its bootup. In that case your system will be mounted under /mnt/sysimage and you can do a 'chroot /mnt/sysimage' and essentially get a command line inside that system.

    Hope that helps.
  • Johan Martinez at Jan 8, 2011 at 8:17 pm

    On Sat, Jan 8, 2011 at 3:50 PM, Lamar Owen wrote:
    On Saturday, January 08, 2011 04:27:39 pm Johan Martinez wrote:

    Now I am booting of CentOS live cd for system restore. I recreated
    partitions like previous system using fdisk and then used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I don't know how to do
    that. Any steps or howto mount LVM manually would be really helpful. I think
    I can recover the system once I am able to access sda1 and sda2. Any
    help?

    pvscan
    vgscan
    vgchange -ay
    lvscan

    (It has been awhile since I have done this; I know the vgchange -ay is
    required, but I don't recall if pvscan and lvscan were required or if I just
    used them for information....but I do think the vgscan was required.)

    In the lvscan output you should see the logical volumes; mount to the
    desired mountpoint with
    mount /dev/VOLUMEGROUP/LOGICALVOLUME MOUNTPOINT

    Or you can reboot the CentOS disk in rescue mode and have it find your
    system as part of its bootup. In that case your system will be mounted
    under /mnt/sysimage and you can do a 'chroot /mnt/sysimage' and essentially
    get a command line inside that system.

    Hope that helps.
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos

    Thanks for the reply Lamar and Robert.

    I had tried pvscan and vgscan before sending out my first mail, but it
    didn't show up any physical volumes and vol grpups.

    I didn't do lvscan though.

    I will try again and see how it goes.

    jM.
    -------------- next part --------------
    An HTML attachment was scrubbed...
    URL: http://lists.centos.org/pipermail/centos/attachments/20110108/57dc7040/attachment.html
  • Johan Martinez at Jan 11, 2011 at 12:49 pm
    On Sat, Jan 8, 2011 at 7:17 PM, Johan Martinez wrote:
    On Sat, Jan 8, 2011 at 3:50 PM, Lamar Owen wrote:
    On Saturday, January 08, 2011 04:27:39 pm Johan Martinez wrote:

    Now I am booting of CentOS live cd for system restore. I recreated
    partitions like previous system using fdisk and then used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I don't know how to do
    that. Any steps or howto mount LVM manually would be really helpful. I think
    I can recover the system once I am able to access sda1 and sda2. Any
    help?

    pvscan
    vgscan
    vgchange -ay
    lvscan

    (It has been awhile since I have done this; I know the vgchange -ay is
    required, but I don't recall if pvscan and lvscan were required or if I just
    used them for information....but I do think the vgscan was required.)

    In the lvscan output you should see the logical volumes; mount to the
    desired mountpoint with
    mount /dev/VOLUMEGROUP/LOGICALVOLUME MOUNTPOINT

    Or you can reboot the CentOS disk in rescue mode and have it find your
    system as part of its bootup. In that case your system will be mounted
    under /mnt/sysimage and you can do a 'chroot /mnt/sysimage' and essentially
    get a command line inside that system.

    Hope that helps.
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos

    Thanks for the reply Lamar and Robert.

    I had tried pvscan and vgscan before sending out my first mail, but it
    didn't show up any physical volumes and vol grpups.

    I didn't do lvscan though.

    I will try again and see how it goes.

    jM.
    I can see PVs sda1 and sda2 with pvscan, but they are not getting mounted as
    lvm. Also, I see sda2 listed as LVM although I didn't partition it that way.
    e.g. fdisk shows it as Linux type and pvscan is showing it as lvm2. That's
    somewhat confusing me.

    Also, the real problem for me is recovery. I don't see LVM mounted after
    doing vgscan and lvscan. Am I missing something here? Any help?

    Thanks you..
    jM
    -------------- next part --------------
    An HTML attachment was scrubbed...
    URL: http://lists.centos.org/pipermail/centos/attachments/20110111/8d91d896/attachment.html
  • Gregory P.. Ennis at Feb 3, 2011 at 7:38 pm
    On Sat, Jan 8, 2011 at 7:17 PM, Johan Martinez wrote:



    On Sat, Jan 8, 2011 at 3:50 PM, Lamar Owen wrote:
    On Saturday, January 08, 2011 04:27:39 pm Johan Martinez
    wrote:
    Now I am booting of CentOS live cd for system restore.
    I recreated
    partitions like previous system using fdisk and then
    used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I
    don't know how to do
    that. Any steps or howto mount LVM manually would be
    really helpful. I think
    I can recover the system once I am able to access sda1
    and sda2. Any help?


    pvscan
    vgscan
    vgchange -ay
    lvscan

    (It has been awhile since I have done this; I know the
    vgchange -ay is required, but I don't recall if pvscan
    and lvscan were required or if I just used them for
    information....but I do think the vgscan was required.)

    In the lvscan output you should see the logical volumes;
    mount to the desired mountpoint with
    mount /dev/VOLUMEGROUP/LOGICALVOLUME MOUNTPOINT

    Or you can reboot the CentOS disk in rescue mode and
    have it find your system as part of its bootup. In that
    case your system will be mounted under /mnt/sysimage and
    you can do a 'chroot /mnt/sysimage' and essentially get
    a command line inside that system.

    Hope that helps.
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos



    Thanks for the reply Lamar and Robert.


    I had tried pvscan and vgscan before sending out my first
    mail, but it didn't show up any physical volumes and vol
    grpups.


    I didn't do lvscan though.


    I will try again and see how it goes.


    jM.




    I can see PVs sda1 and sda2 with pvscan, but they are not getting
    mounted as lvm. Also, I see sda2 listed as LVM although I didn't
    partition it that way. e.g. fdisk shows it as Linux type and pvscan is
    showing it as lvm2. That's somewhat confusing me.


    Also, the real problem for me is recovery. I don't see LVM mounted after
    doing vgscan and lvscan. Am I missing something here? Any help?


    Thanks you..
    jM

    ------------------------------------------------------------------------

    Johan,

    I have the same circumstance, and have not been able to mount an lvm
    volume to a new machine. I have your posts, but have not been able to
    mount the lvm either. Did you ever get this resolved? Sure would
    appreciate your thoughts, or any one else that has been able to do this.

    Greg
  • Gregory P.. Ennis at Feb 3, 2011 at 8:50 pm
    On Sat, Jan 8, 2011 at 7:17 PM, Johan Martinez wrote:



    On Sat, Jan 8, 2011 at 3:50 PM, Lamar Owen wrote:
    On Saturday, January 08, 2011 04:27:39 pm Johan Martinez
    wrote:
    Now I am booting of CentOS live cd for system restore.
    I recreated
    partitions like previous system using fdisk and then
    used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I
    don't know how to do
    that. Any steps or howto mount LVM manually would be
    really helpful. I think
    I can recover the system once I am able to access sda1
    and sda2. Any help?


    pvscan
    vgscan
    vgchange -ay
    lvscan

    (It has been awhile since I have done this; I know the
    vgchange -ay is required, but I don't recall if pvscan
    and lvscan were required or if I just used them for
    information....but I do think the vgscan was required.)

    In the lvscan output you should see the logical volumes;
    mount to the desired mountpoint with
    mount /dev/VOLUMEGROUP/LOGICALVOLUME MOUNTPOINT

    Or you can reboot the CentOS disk in rescue mode and
    have it find your system as part of its bootup. In that
    case your system will be mounted under /mnt/sysimage and
    you can do a 'chroot /mnt/sysimage' and essentially get
    a command line inside that system.

    Hope that helps.
    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos



    Thanks for the reply Lamar and Robert.


    I had tried pvscan and vgscan before sending out my first
    mail, but it didn't show up any physical volumes and vol
    grpups.


    I didn't do lvscan though.


    I will try again and see how it goes.


    jM.




    I can see PVs sda1 and sda2 with pvscan, but they are not getting
    mounted as lvm. Also, I see sda2 listed as LVM although I didn't
    partition it that way. e.g. fdisk shows it as Linux type and pvscan is
    showing it as lvm2. That's somewhat confusing me.


    Also, the real problem for me is recovery. I don't see LVM mounted after
    doing vgscan and lvscan. Am I missing something here? Any help?


    Thanks you..
    jM

    ------------------------------------------------------------------------

    Johan,

    I have the same circumstance, and have not been able to mount an lvm
    volume to a new machine. I have your posts, but have not been able to
    mount the lvm either. Did you ever get this resolved? Sure would
    appreciate your thoughts, or any one else that has been able to do this.

    Greg
    -------------------------------------------
    Johan,

    I am not sure if this is your problem but what I can determine is that
    there may be a conflict with the same names of the lvm volumes; ie the
    old volume that I am trying to mount has the same name as the volume on
    the machine that is active.

    [root at SeVi mnt]# pvscan
    PV /dev/hdc2 VG VolGroup00 lvm2 [37.16 GB / 0 free]
    PV /dev/hdd1 VG VolGroup00 lvm2 [186.28 GB / 0 free]
    PV /dev/sda2 VG VolGroup00 lvm2 [931.41 GB / 0 free]
    Total: 3 [1.13 TB] / in use: 3 [1.13 TB] / in no VG: 0 [0 ]
    [root at SeVi mnt]# lvchange --available y /dev/VolGroup00/LogVol00
    [root at SeVi mnt]# mount /dev/VolGroup00/LogVol00 /mnt/hdc2

    This results in mounting the current machine's lvm which is on sda1, but
    I am wanting to mount /dev/hdc2.

    Any one have any ideas ?

    Greg
  • Compdoc at Feb 3, 2011 at 9:27 pm
    I am not sure if this is your problem but what I can determine is that
    there may be a conflict with the same names of the lvm volumes; ie the old
    volume that I am trying to mount has the same name as the volume on the
    machine that is active.


    I was wondering if you were running into that problem. I've run into it in
    the past. Centos always uses the same logical group and logical volume names
    as default for a new install, and you can't mount a foreign LVM if the names
    conflict.

    I once set up a test system to try to recover some files from an LVM, and
    installed centos with no LVM to avoid the conflict, but centos didn't
    install the lvm tools automatically . (I like using system-config-lvm)
    However, the tools are easy enough to install with yum. Some live CDs let
    you install system-config-lvm too.

    You can also use unique LVM group and vol names when installing centos to
    avoid this...
  • Nico Kadel-Garcia at Feb 3, 2011 at 9:39 pm

    On Thu, Feb 3, 2011 at 9:27 PM, compdoc wrote:
    I am not sure if this is your problem but what I can determine is that
    there may be a conflict with the same names of the lvm volumes; ie the old
    volume that I am trying to mount has the same name as the volume on the
    machine that is active.
    Note that CentOS 6 will not. RedHat rewrote anaconda to use the
    hostname in the volume groups, which is very helpful to avoid just
    this situation.
    I was wondering if you were running into that problem. I've run into it in
    the past. Centos always uses the same logical group and logical volume names
    as default for a new install, and you can't mount a foreign LVM if the names
    conflict.

    I once set up a test system to try to recover some files from an LVM, and
    installed centos with no LVM to avoid the conflict, but centos didn't
    install the lvm tools automatically . (I like using system-config-lvm)
    However, the tools are easy enough to install with yum. Some live CDs let
    you install system-config-lvm too.

    You can also use unique LVM group and vol names when installing centos to
    avoid this...





    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
  • Gregory P.. Ennis at Feb 4, 2011 at 12:21 am

    On Thu, Feb 3, 2011 at 9:27 PM, compdoc wrote:
    I am not sure if this is your problem but what I can determine is that
    there may be a conflict with the same names of the lvm volumes; ie the old
    volume that I am trying to mount has the same name as the volume on the
    machine that is active.
    Note that CentOS 6 will not. RedHat rewrote anaconda to use the
    hostname in the volume groups, which is very helpful to avoid just
    this situation.
    I was wondering if you were running into that problem. I've run into it in
    the past. Centos always uses the same logical group and logical volume names
    as default for a new install, and you can't mount a foreign LVM if the names
    conflict.

    I once set up a test system to try to recover some files from an LVM, and
    installed centos with no LVM to avoid the conflict, but centos didn't
    install the lvm tools automatically . (I like using system-config-lvm)
    However, the tools are easy enough to install with yum. Some live CDs let
    you install system-config-lvm too.

    You can also use unique LVM group and vol names when installing centos to
    avoid this...
    -----------------------------------------------------------------------

    Nico,

    Thanks for the response. Does this mean there is nothing I can do to
    make this happen. Is there a way to change the name of "VolGroup00"?
    If so I have not found it yet. I see that I can change "LogVol00", but
    have not figured out how to chanage "VolGroup00".

    Maybe, I am finally beginning to understand logical volumes. :)

    Greg
  • JohnS at Feb 4, 2011 at 12:35 am

    On Thu, 2011-02-03 at 23:21 -0600, Gregory P.. Ennis wrote:

    Thanks for the response. Does this mean there is nothing I can do to
    make this happen. Is there a way to change the name of "VolGroup00"?
    If so I have not found it yet. I see that I can change "LogVol00", but
    have not figured out how to chanage "VolGroup00".
    It is "vgrename" and please use plain test for emails.

    John
  • Gregory P. Ennis at Feb 4, 2011 at 11:06 am

    On Thu, 2011-02-03 at 23:21 -0600, Gregory P.. Ennis wrote:

    Thanks for the response. Does this mean there is nothing I can do to
    make this happen. Is there a way to change the name of "VolGroup00"?
    If so I have not found it yet. I see that I can change "LogVol00", but
    have not figured out how to chanage "VolGroup00".
    It is "vgrename" and please use plain test for emails.

    John

    -----------------------------------------------------------------

    John,

    Thanks for your note. I tried to change the name and this is what I get :

    [root at SeVi ~]# vgrename /dev/VolGroup00 /dev/SeViGroup00
    Volume group "VolGroup00" still has active LVs
    Internal error: Volume Group SeViGroup00 was not unlocked
    Device '/dev/sda2' has been left open.
    Device '/dev/sda2' has been left open.
    Device '/dev/sda2' has been left open.

    Sorry, if my previous note was not plain text .... thought that it was.

    I am about ready to regen a new os without the use of LVM, my thought is
    that I should be able use that to mount the lvm volumes I am trying to
    recover. If you or others have any other ideas I would appreciate your
    help.

    Greg
  • Nico Kadel-Garcia at Feb 4, 2011 at 5:40 pm

    On Fri, Feb 4, 2011 at 11:06 AM, Gregory P. Ennis wrote:
    On Thu, 2011-02-03 at 23:21 -0600, Gregory P.. Ennis wrote:

    Thanks for the response. ?Does this mean there is nothing I can do to
    make this happen. ?Is there a way to change the name of "VolGroup00"?
    If so I have not found it yet. ?I see that I can change "LogVol00", but
    have not figured out how to chanage "VolGroup00".
    It is "vgrename" and please use plain test for emails.

    John

    -----------------------------------------------------------------

    John,

    Thanks for your note. ?I tried to change the name and this is what I get :

    [root at SeVi ~]# vgrename /dev/VolGroup00 /dev/SeViGroup00
    ?Volume group "VolGroup00" still has active LVs
    ?Internal error: Volume Group SeViGroup00 was not unlocked
    ?Device '/dev/sda2' has been left open.
    ?Device '/dev/sda2' has been left open.
    ?Device '/dev/sda2' has been left open.

    Sorry, if my previous note was not plain text .... thought that it was.
    I keep a spare box around with non-default LVM names, actually using
    direct partitions, for precisely this reason. It's particularly
    important if for virtualization servers when you've got a stack of
    virtual images and their LVM names conflict with that of your host
    server.

    It's also another reason it's handy to be able to boot with a live CD.
    I am about ready to regen a new os without the use of LVM, my thought is
    that I should be able use that to mount the lvm volumes I am trying to
    recover. ?If you or others have any other ideas I would appreciate your
    help.
    This is probably your fastest method.
  • Gregory P. Ennis at Feb 4, 2011 at 7:15 pm

    On Fri, Feb 4, 2011 at 11:06 AM, Gregory P. Ennis wrote:
    On Thu, 2011-02-03 at 23:21 -0600, Gregory P.. Ennis wrote:

    Thanks for the response. Does this mean there is nothing I can do to
    make this happen. Is there a way to change the name of "VolGroup00"?
    If so I have not found it yet. I see that I can change "LogVol00", but
    have not figured out how to chanage "VolGroup00".
    It is "vgrename" and please use plain test for emails.

    John

    -----------------------------------------------------------------

    John,

    Thanks for your note. I tried to change the name and this is what I get :

    [root at SeVi ~]# vgrename /dev/VolGroup00 /dev/SeViGroup00
    Volume group "VolGroup00" still has active LVs
    Internal error: Volume Group SeViGroup00 was not unlocked
    Device '/dev/sda2' has been left open.
    Device '/dev/sda2' has been left open.
    Device '/dev/sda2' has been left open.

    Sorry, if my previous note was not plain text .... thought that it was.
    I keep a spare box around with non-default LVM names, actually using
    direct partitions, for precisely this reason. It's particularly
    important if for virtualization servers when you've got a stack of
    virtual images and their LVM names conflict with that of your host
    server.

    It's also another reason it's handy to be able to boot with a live CD.
    I am about ready to regen a new os without the use of LVM, my thought is
    that I should be able use that to mount the lvm volumes I am trying to
    recover. If you or others have any other ideas I would appreciate your
    help.
    This is probably your fastest method.

    --------------------------------------------------------------

    Thanks Nico,

    Great Advice, am a little surprised I had not had this problem before now.

    Greg
  • JohnS at Feb 5, 2011 at 9:16 am

    On Fri, 2011-02-04 at 10:06 -0600, Gregory P. Ennis wrote:

    [root at SeVi ~]# vgrename /dev/VolGroup00 /dev/SeViGroup00
    Volume group "VolGroup00" still has active LVs
    Internal error: Volume Group SeViGroup00 was not unlocked
    Device '/dev/sda2' has been left open.
    Device '/dev/sda2' has been left open.
    Device '/dev/sda2' has been left open.
    man vgrename....

    All the Volume Groups visible to a system need to have different
    names. Otherwise many LVM2 commands will refuse to run or give warning
    mes-sages.

    Try by using "vgdisplay" to get the UUID and use the "UUID" to
    "vgrename" otherwise start unpluging drive cables to get to the LVM you
    need to rename.

    John
  • Robert Heller at Jan 8, 2011 at 6:03 pm

    At Sat, 8 Jan 2011 15:27:39 -0600 CentOS mailing list wrote:


    Hi,

    I am trying to recover data from my old system which had LVM. The disk had
    two partitions - /dev/sda1 (boot, Linux) and /dev/sda2 (Linux LVM). I had
    taken a backup of both partitions using dd.

    Now I am booting of CentOS live cd for system restore. I recreated
    partitions like previous system using fdisk and then used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I don't know how to do
    that. Any steps or howto mount LVM manually would be really helpful. I think
    I can recover the system once I am able to access sda1 and sda2. Any help?
    You will need to do a vgscan to scan for the LVM volumn you created.
    Once scanned, you can then mount the file system(s) there, either using
    the mapper files (/dev/mapper/volumegroup-volumn) or the mount labels
    (LABEL=label). If this was a stock CentOS install, the root file system
    will be labeled '/' and the /boot file system will be labeled '/boot':

    mkdir /mnt/sysimage
    mount -v LABEL=/ /mnt/sysimage
    mount -v LABEL=/boot /mnt/sysimage/boot

    jM.

    MIME-Version: 1.0

    _______________________________________________
    CentOS mailing list
    CentOS at centos.org
    http://lists.centos.org/mailman/listinfo/centos
    --
    Robert Heller -- 978-544-6933 / heller at deepsoft.com
    Deepwoods Software -- http://www.deepsoft.com/
    () ascii ribbon campaign -- against html e-mail
    /\ www.asciiribbon.org -- against proprietary attachments
  • Kwan Lowe at Jan 11, 2011 at 1:47 pm

    On Sat, Jan 8, 2011 at 4:27 PM, Johan Martinez wrote:
    Hi,
    I am trying to recover data from my old system which had LVM. The disk had
    two partitions - /dev/sda1 (boot, Linux) and /dev/sda2 (Linux LVM).?I had
    taken a backup of both partitions using dd.
    Now I am booting of CentOS live cd for system restore. I recreated
    partitions like previous system using fdisk and then used dd to dump all the
    data onto it. I would like to mount sda2 as LVM, but I don't know how to do
    that. Any steps or howto mount LVM manually would be really helpful. I think
    I can recover the system once I am able to access sda1 and sda2. Any help?
    jM.
    Once you do the pvscan and vgscan, then vgchange, you should have the
    LVs available in /dev/VGNAME/LVNAME. For example, if your volume
    group name is VolGroup00, the LVs will be /dev/VolGroup00/lv001, etc..

    Keep in mind that you are not mounting sda2 in this case but rather
    the LVs associated with the VG associated with the PV on sda2.

    For example:
    pvscan
    vgscan
    vgchange -ay VolGroup00
    mkdir /mnt/tmp1
    mount /dev/VolGroup00/lv01 /mnt/tmp1


    Also note that in some cases the lvm tools must be called by
    specifying lvm before the command

    lvm pvscan
    lvm vgchange -ay VolGroup00

    etc..
  • Lamar Owen at Jan 11, 2011 at 3:46 pm

    On Tuesday, January 11, 2011 01:47:54 pm Kwan Lowe wrote:
    Also note that in some cases the lvm tools must be called by
    specifying lvm before the command

    lvm pvscan
    lvm vgchange -ay VolGroup00
    To have in the archive, note that this is the case in the dracut shell (accessed at boot on error if the RDSHELL argument is passed) that should be in C6 (as it's in F12 and later). Having the RDSHELL boot argument is very nice, as if you get error during boot that won't even allow single user mode (things like can't find root device, or a module failed to load, etc) you can get a rudimentary shell in the initial ramdisk environment.

    See http://fedoraproject.org/wiki/How_to_debug_Dracut_problems for a lot more info.

    Having said that, I've not tried on a live EL6 system as yet, so YMMV, of course.

Related Discussions