How to provide a block device for partition in a hard drive image?

dgar · 12-04-2008, 09:11 PM

I'm configuring a kvm hosting machine with the following device stack:

Code:

    rootfs swap
       |    /
     lvol lvol
       | /
       vg
 boot  |
   \   pv
     \ |
    drbd
      |
    lvol
      |
     vg
      |
     pv
      |
    /dev/sda
      |
    3ware
     / \
    d1 d2

So here is the problem. The lvol is too small. I shut down the guestVM, unattached the drbd driver, and extended the lvol size.

Now how do I run resize2fs on the second partition of the hard drive image in the lvol? I found a neat trick to mount the partition with the following offest:

Code:

dan@xen:~$ sudo parted /dev/mapper/vg-ftl_www unit B print
[sudo] password for dan: 
Model: Linux device-mapper (dm)
Disk /dev/mapper/vg-ftl_www: 10737418240B
Sector size (logical/physical): 512B/512B
Partition Table: msdos

Number  Start       End           Size          Type     File system  Flags
 1      32256B      106928639B    106896384B    primary  ext3         boot 
 2      106928640B  10733990399B  10627061760B  primary               lvm

Any ideas short of dumping the entire lvol, split it, resize and reassemble? Google has failed me, and it hasn't in a very, very long time.

dgar · 12-04-2008, 09:17 PM

kpartx -a -v /dev/mapper/vg-ftl_www