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

[Russell Allred]

On Tuesday, April 4, 2023 at 4:36:25 PM UTC-7, gah4 wrote:
> On Tuesday, April 4, 2023 at 4:04:59 PM UTC-7, Arne Vajhøj wrote: 
> 
> (snip)
> > 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
> Some controller (or computer) might be able to do that. 
> 
> It isn't obvious that an intermediate state is good, though, 
> so you probably want a full backup before starting it. 
> 
> Seems to me that with appropriate checkpoint, so that it 
> remembers how for it has gone, and how far still to go, 
> that it words. And likely when no-one else is writing. 
> 
> You can generate the whole new contents of disk4, 
> without changing the other ones. Some disk space, 
> somewhere else, for temporary use would be nice. 
> Copy some blocks to temporary space, record that 
> you did that somewhere, generate new blocks for 
> those parts of the disks. Repeat until done. 
> 
> If it fails partway through, continue on based on 
> the known stored temporary blocks.

I get the theory part ok. It's can the MSA$UTIL program and my P400 controller do it? If so, what are the commands? I have found this link which helps:

http://h41379.www4.hpe.com/doc/84final/6048/6048pro_052.html#bottom_052

I hope someone has tried this and can show me examples of the commands to use and pitfalls to avoid.