Mike Hardy wrote:

Max Waterman wrote:

quoted

OK, I am going to try to expand the capacity of my raid5 array and I 
want to make sure I've got it right.

Not a bad idea, as its all or nothing...

quoted

Disk /dev/hdg: 200.0 GB, 200049647616 bytes
Disk /dev/hdi: 200.0 GB, 200049647616 bytes
Disk /dev/hdk: 200.0 GB, 200049647616 bytes
Disk /dev/sda: 200.0 GB, 200049647616 bytes
Disk /dev/sdb: 200.0 GB, 200049647616 bytes
Disk /dev/sdc: 200.0 GB, 200049647616 bytes
Disk /dev/sdd: 200.0 GB, 200049647616 bytes

They certainly all looked the same (including the C/H/S counts)

quoted

This leaves me with sdc which I can try to add. If that goes OK, I'll 
trash the backup and add sd[ab] too.

I'd be very wary of this, for two reasons. One, you have the backup 
during the add for a reason. If anything goes wrong, there goes your 
data. Second, where would you ever back your raid up to? What about fs 
corruption?

The rule of thumb with databases is to always have enough contiguous 
scratch space to dump and restore your biggest table. With large RAID, 
you should always be able to dump and restore your largest raid device, 
imho. Its a bunch more disk yes, but you'll need it at some point, I 
promise. Many future tears can be averted...

I'm not worried about losing my data enough to make regular backups.
I recently thought I'd lost all my data - it wasn't that much of a 
shock. I since discovered I hadn't lost it all, so all is well.

I've made a backup onto a spare array, plus onto one of the 200GB disks 
which I will use as a spare later.

quoted

3) Are there any instructions for raidreconfig? I understand is uses 
some non-mdadm config files as from/to input.

the man page is great - honest. Two conf files (current and future) and 
you're set

Yeah, but I don't know how to use raidconf files. I use mdadm. I 
currently have in my mdadm.conf :

DEVICE /dev/hd[egik]
ARRAY /dev/md0 level=raid5 num-devices=4  devices=/dev/hd[egik]

I think my target mdadm.conf would be :

DEVICE /dev/hd[egik] /dev/sd[abc]
ARRAY /dev/md0 level=raid5 num-devices=7
devices=/dev/hd[egik],/dev/sd[abc]

What are these in raidtab(5) terms?

Max.