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Converting RAID 5 to RAID 1

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Occasional Advisor

Converting RAID 5 to RAID 1

I am converting a RAID 5 Array to a RAID 1 Array. Following is the steps involved:
1. Moving the datafiles to a different filesystem in a different array.
2. Unmount all the filesystems in the array and delete the logical volumes for those FS.
3. Unconfigure the Volume group for that Array
(only array in the Volume group).
4. Create new LUNs with RAID1 array from the free disks.
5. Create a new volume group with all the new LUNs.
6. Create new Filesystems and use it.

Is there any precauiton i need to take apart from the FS backups or any additional steps involved.

Honored Contributor

Re: Converting RAID 5 to RAID 1

Hi Milan,

to convert a RAID 5 LUN top RAID 1, these are the steps, i guess.

Move data from existing LUN to other disk(s).
Remove entries in fstab for the existing LUN.
vgreduce the vg to remove the LUN from vg
delete the LUN and recreate the new LUN.
Reboot the system to identify the newly created LUN(S)
Add the new LUN to the VG, use vgextend
Create LV's, use lvcreate.
Move data to new LV's

hope this helps.

Roger Baptiste
Honored Contributor

Re: Converting RAID 5 to RAID 1


Identify the disks belonging
to the RAID 5 array, using
ioscan ouput.
Run a pvdisplay on these
disks and grab the LV names.

Correlate these LV''s with
filesystems and make a copy
of the filesystems.

Then, unmount FS, deactivate the vg''s
and export it. (no need
ro remove lv''s remove vg'..)

Remove entries of fs in
fstab, backup list and wherever it is refered.

Once you complete the RAID 1
array setup, recreate new VG''s . lv''s, fs''s.

If the disks contain database, you would need to
involve DBA in the process
of taking backup and coordinating the removal.
Make sure there are no raw volumes out there.

Take it easy.