How do I know what physical drives/partitions are behind my /dev/mapper/isw_dghbbcaabe_RAID_Volume11?

Question

This is a just upgraded Ubuntu 10.04.1 LTS machine.

The /dev/mapper/isw_dghbbcaabe_RAID_Volume11 is "new" to the upgrade but I don´t know what physical drives/partitions are included in the "device".

I have tried

root@barabasi:~# blkid   
/dev/sda1: UUID="8258e116-265a-4797-59d1-fae72a643620" TYPE="swap" 
/dev/sdb: TYPE="isw_raid_member" 
/dev/mapper/isw_dghbbcaabe_RAID_Volume11: UUID="1d4721b1-5649-4772-8a03-5c3db81eba1b" TYPE="ext3" 
/dev/mapper/isw_dghbbcaabe_RAID_Volume15: UUID="b9a639af-dee8-4e0c-90f6-15432efac4f2" TYPE="swap"

and

root@barabasi:~# ls -alh /dev/disk/by-uuid/  
total 0 
drwxr-xr-x 2 root root 100 2011-01-14 12:49 . 
drwxr-xr-x 5 root root 100 2011-01-14 12:49 .. 
lrwxrwxrwx 1 root root 41 2011-01-14 12:49 1d4721b1-5649-4772-8a03-5c3db81eba1b ->    ../../mapper/isw_dghbbcaabe_RAID_Volume11 
lrwxrwxrwx 1 root root 10 2011-01-14 12:49 8258e116-265a-4797-59d1-fae72a643620 -> ../../sda1 
lrwxrwxrwx 1 root root 41 2011-01-14 12:49 b9a639af-dee8-4e0c-90f6-15432efac4f2 -> ../../mapper/isw_dghbbcaabe_RAID_Volume15

But I still don´t know what physical drives are involved.

Answer 1

You can use dmsetup. Invoke:

$ sudo dmsetup -v table /dev/mapper/isw_dghbbcaabe_RAID_Volume11

That will give you a list of sectors which are mapped to another device. In my case (encrypted root partition), I get the following output:

$ sudo dmsetup table /dev/mapper/hacki-mobile 
0 567028121 crypt aes-cbc-essiv:sha256 0000000000000000000000000000000000000000000000000000000000000000 0 8:6 2056

That means that sectors 0-567028121 are mapped to a device with major/minor number 8/6. That is the 6th partition on my sda drive, as you can see with:

$ ls -Al /dev/sda6
brw-rw---- 1 root disk 8, 6 2010-12-21 14:38 /dev/sda6

Your output from dmsetup maybe a bit different, as I'm on Ubuntu 10.04