[HLUG] backup old disk

[Andrew Hodgson]

Hi,

It looks like you have a /boot partition, then the rest is mounted in an LVM system.  The LVM probably has multiple volumes, for the SWAP and various data partitions.

Use the LVM command to get to the LVM prompt, then run lvdisplay to view the volumes.  You can mount these from /dev/mapper/lvmgroup-lvmvolume or /dev/lvmgroup/lvmvolume.

Here is output of the lvdisplay command on my test RHEL5 system:

  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol00
  VG Name                VolGroup00
  LV UUID                B5KpIt-54IK-sCdc-7Ae9-KsXb-zeYv-4A5fLE
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                66.19 GB
  Current LE             2118
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:0

  --- Logical volume ---
  LV Name                /dev/VolGroup00/LogVol01
  VG Name                VolGroup00
  LV UUID                bFVr3y-glrV-LNEQ-Tz7w-Mvqz-Me1E-QwXEEB
  LV Write Access        read/write
  LV Status              available
  # open                 1
  LV Size                1.94 GB
  Current LE             62
  Segments               1
  Allocation             inherit
  Read ahead sectors     0
  Block device           253:1

LogVol00 is the data volume, LogVol01 is swap, and they both belong to the LVM group VolGroup00.  These were created by the RHEL installer, and so why we get the generic names :).

Thanks.
Andrew.

-----Original Message-----
From: Graham Cole [mailto:grahamcole at nerdshack.com] 
Sent: 12 July 2007 10:32
To: Herefordshire Linux Users Group.
Subject: [HLUG] backup old disk

Thanks John, it's about time I understood the partitions but "extended"
and "Linux LVM" are jargon I don't understand. Both seem to be big so
neither is a swap partition I guess.

~$ sudo fdisk -l /dev/hdc

Disk /dev/hdc: 20.4 GB, 20490559488 bytes
255 heads, 63 sectors/track, 2491 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/hdc1   *           1          31      248976   83  Linux
/dev/hdc2              32        2491    19759950    5  Extended
/dev/hdc5              32        2491    19759918+  8e  Linux LVM

This is what I got:

~$ sudo mount -t ext3 /dev/hdc2 /mnt/disk2
mount: wrong fs type, bad option, bad superblock on /dev/hdc2,
       missing codepage or other error
       (aren't you trying to mount an extended partition,
       instead of some logical partition inside?)
       In some cases useful info is found in syslog - try
       dmesg | tail  or so

:~$ sudo mount -t ext3 /dev/hdc5 /mnt/disk2
mount: /dev/hdc5 already mounted or /mnt/disk2 busy

Not busy!? I did umount and checked that /mnt/disk2 was empty. Can it be
busy while empty? Maybe it's something else and the error message is
garbled info

Graham






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