[Info-vax] Raid 5 Add Disk to Raid 5 with p400 and MSA$UTIL

[Arne Vajhøj]

On 4/4/2023 5:21 PM, Russell Allred wrote:
> I have 3 300Gb SAS drives running raid 5. It's almost out of space. I
> have added a new matching drive I can see with the MSA$UTIL show
> options.  The new drive is disk 4. Can I add it to the existing RAID
> 5 without hurting the data and get more free blocks? I do not know
> how this works.  2. The firmware on the new drive is HPD2. On the
> older ones it HPD5. Will that matter?  3. My cache battery is dead
> can I safely work on these drives? Here is what I see in MSA:

A major reorg of data will be needed, but whether that requires:

old RAID-5 disk system -> other media -> new RAID-5 disk system

or the RAID controller can actually handle it automatically I don't 
know. Someone that know that RAID controller may be able to tell.

But just to understand the basics:

old system:

disk1          disk2          disk3
blk 1          blk 2          blk 1 xor 2
blk 3          blk 3 xor 4    blk 4
blk 5 xor 6    blk 5          blk 6

new system:

disk1             disk2             disk3             disk4
blk 1             blk 2             blk 3             blk 1 xor 2 xor 3
blk 4             blk 5             blk 4 xor 5 xor 6 blk 6

Arne