Disk mirroring question

[stevkov]

There is p640 (7026-B80) with two hard disks, one of the disks has potential problems (21a00001), the person that works on the server claims that they have "disk to disk" mirroring, is there any way to check is this mirroring working ok?

also, what will happen if we take out the problem disk?

Will the server continue to work without any problems?

If this helps, this is the same server i had problems via upgrading the ML on AIX 4.3.3.

 

[hirschaj]

Provide output from "lsvg -l rootvg".

There are specific methods for removing a mirrored disk, but yes, you can remove one of a mirrored set and keep on trucking.


Jim Hirschauer

http://www.aixexpert.com

 

[needcoffee]

lsvg -l rootvg

This will show you the lv's in rootvg. Check the LP, PP, and PV columns for hd4.

LP is the # of logical partitions for the LV.
PP is the # of physical partitions for the LV.
PV is the # of physical disks in the that the LV is on.

If the PP is double the LP value and PV is 2 then the LV is mirrored between 2 disks. All of the other lv's in rootvg should show this way unless the TYPE is sysdump.

needcoffee

 

[hirschaj]

Hey needcoffee, I like your signature


Jim Hirschauer

http://www.aixexpert.com

 

[p5wizard]

Also better make sure that all LVS are mirrored from one disk to the other... This is normally the case, but a check won't harm you...

use the following piece of code:

lsvg -l rootvg|tail +3|while read lvname lvtype junk
do
 echo "${lvname} (${lvtype}) mirror map:"
 lslv -m ${lvname}|tail +3|awk '{print $3,$5}'|uniq
 echo
done

you should see something like in the output:

-----------------------------------
hd5 (boot) mirror map:
hdisk2 hdisk0

hd6 (paging) mirror map:
hdisk2 hdisk0

hd8 (jfslog) mirror map:
hdisk2 hdisk0

hd4 (jfs) mirror map:
hdisk2 hdisk0

hd2 (jfs) mirror map:
hdisk2 hdisk0

hd9var (jfs) mirror map:
hdisk2 hdisk0

hd3 (jfs) mirror map:
hdisk2 hdisk0

hd1 (jfs) mirror map:
hdisk2 hdisk0

hd10opt (jfs) mirror map:
hdisk2 hdisk0

hd7 (sysdump) mirror map:
hdisk2
-----------------------------------

If you see twice the same disk name anywhere, then not all your LP mirrors are placed correctly on both disks...




HTH,

p5wizard

 

[costiles]

I use the smitty menu to check mirroring. smitty lv <cr>
You should see PPs double LPs and it should say open/syncd - not open/stale. And you need to make sure that all the file systems in that volume group say the above!

 

[bi]

One thing not stated in the replies to this thread is that you want to make sure quorum is turned off for the volume group after all LVs in the volume group are mirrored.

Having quorum on tells the system to vary off the volume group if more than 50% of the disks are lost. If you have, for example, a two disk volume group that is mirrored and quorum is still on, the volume group will vary off if you lose one of the disks, even though the volume group could still be working on the one good disk that is left.