Removing devices on RHEL 4 and 5

earlysame55 · 10-21-2010, 07:43 PM

Dear Gurus

Need to remove the following LV. I cannot drill down to the level of which disks it's made up with. Please validate my response.
PS: Server was not built and managed by me and there is a lack of documentation.

Please refer : http://paste.org/pastebin/view/23848

Now the question.

I get to see the lv is made up of dm-7 and dm-9. On the partition table dm-7 has the mjor:minor as :
253 7 23068672 dm-7
and dm-9 is:
253 9 23068672 dm-9

now the problem is finding what these 2 devices are, luckily i see the same major:minor numbers in /dev/mapper directory

brw-rw---- 1 root disk 253, 9 Oct 13 15:49 temp
brw-rw---- 1 root disk 253, 7 Oct 13 15:49 temp_1

QUESTION 1
is
dm-7 --> temp_1
dm-9 --> temp

Now i did another guess to find out what these 2 were. This is a guess, there was no science and methodology behind my guess. I need to know if my approach was right, if not what is the right way of doing it.

Here are the 2
temp (360060e8005b24f000000b24f00007500)
[size=22 GB][features="1 queue_if_no_path"][hwhandler="0"]
\_ round-robin 0 [prio=2][active]
\_ 0:0:0:7 sdd 8:48 [active][ready]
\_ 1:0:0:7 sdk 8:160 [active][ready]

temp_1 (360060e8005b24f000000b24f00007501)
[size=22 GB][features="1 queue_if_no_path"][hwhandler="0"]
\_ round-robin 0 [prio=2][active]
\_ 0:0:0:8 sde 8:64 [active][ready]
\_ 1:0:0:8 sdl 8:176 [active][ready]

now i see multipathd is not configured to run
chkconfig --list | grep multi
multipathd off on all the levels

ps -ef | grep -i multi
root 24365 17927 0 08:21 pts/7 00:00:00 grep -i multi

Again the question is how to drill down and find where my devices are coming from which make up the temp_lv.

Part 2
-------
How do i get rid of these devices the proper way if they are the correct devices.

TIA

rayfordj · 10-21-2010, 10:30 PM

OK, here goes; see if I followed correctly...

temp_lv is the only LV in the temp_vg VG which is comprised of two mpath devices temp (currently sdd and sdk) and temp_1 (currently sde and sdl).

It looks like you drilled down through the layers identifying each participating component already, so it is just a matter of procedurally backing out the configuration. If you want to remove the LV, it is just a matter of ensuring the the LV is not mounted, edit fstab to prevent the system from attempting to mount the LV during boot, deactivate the LV, remove the LV.

Code:

# #umount /where/ever/it/is/mounted
# #comment entry in /etc/fstab to prevent mount attempt during boot
# lvchange -an /dev/temp_vg/temp_lv
# lvremove /dev/temp_vg/temp_lv

To continue...
If native multipathing (dm-multipath) is not being used, then something has leveraged device-mapper multipath to create the two mpath devices and this should be identified and suppressed before continuing down the layers and removing the LUNs/disks.

Code:

# vgchange -an /dev/temp_vg
# vgremove /dev/temp_vg
# pvremove /dev/mpath/temp /dev/mpath/temp_1
# #break down the mpath devices and suppress creation attempt
# #remove LUNs/disks

NOTE: depending on the package versions some of the options and/or arguments might vary. For example, lvremove /dev/temp_vg/temp_lv or lvremove temp_vg/temp_lv. Please consult the documentation for binary version specific options, parameters, and syntax.