>>>>> On Tue, 4 Apr 2000, "Gregory" == Gregory Leblanc wrote:
+> I've found some cash, and want to add a spare disk to our
+> raid5 array for
+> added redundancy.
+> Can this be done? It is a matter of
+> 1. raidstop
+> 2. add spare to raidtab
+> 3. raidhotadd spare
Gregory> This gives you a hot spare, is that what you want?
Yes, I want to add a spare disk. I added the following to my /etc/raidtab:
device /dev/hdd1
spare-disk 0
and changed nr-spare-disks from 0 to 1. Then I did a raidhotadd. The disk was
larger than the rest by a bit, but I figured that extra space would just be
wasted. The disk seemed to add in just fine, but mdstat looked like:
[root@osmin /root]# cat /proc/mdstat
Personalities : [raid5]
read_ahead 1024 sectors
md1 : active raid5 hdd1[4] hdk1[3] hdi1[2] hdg1[1] hde1[0] 100251264 blocks level 5,
32k chunk, algorithm 2 [4/4] [UUUU]
unused devices: <none>
The 4/4 and unused devices <none> left me wondering if my spare was
recognised. I mean I see it in the md1 line above, but did it add as a spare?
Anyway, because of the as yet unexplained and very scary:
raid5: bug: stripe->bh_new[2], sector 9846456 exists
I had done this all in single-user mode, so I had no logs to examine. After my
first multi-user boot, I see the following:
raid5 personality registered
md1: max total readahead window set to 384k
md1: 3 data-disks, max readahead per data-disk: 128k
raid5: spare disk hdd1
raid5: device hdk1 operational as raid disk 3
raid5: device hdi1 operational as raid disk 2
raid5: device hdg1 operational as raid disk 1
raid5: device hde1 operational as raid disk 0
raid5: allocated 4248kB for md1
raid5: raid level 5 set md1 active with 4 out of 4 devices, algorithm 2
which seems to indicate that everything is kosher. Still not sure about the
partition size mismatch, guess I'll find out when one trips and the
reconstruction begins.
+> or is it more a matter of
+> 1. raidstop
+> 2. cry
+> 3. mkraid with the "I really mean it"
+> 4. restore data from backup
Gregory> This lets you expand the capacity of the RAID, is that what you want?
Gregory> Greg
No, I definitely wanted a spare. Thanks for the reply!
-Darren
