RE: opensolaris and raid-x

["Ian Lowe" <ianlowe@xxxxxxxxxxxxxxxxx>]

This feature set of being able to use disparate sized disks (the size
of
given raid set partitions has to be the same, but the "lost"
space can be
used in another set), dynamically add devices, grow and reshape the array
was one of my reasons for going with Ubuntu 7.10 for my home server.



In my case, I used my disks in the following way:



Four 500Gb Samsung Spinpoints -



I made a 20Gb partition on disks 1 and 2, and configured this as a RAID-1
mirror set - the OS is installed here, and this is where the machine boots
from.



On all five disks I then created a 480Gb partition - these were combined
into a  1.9Tb RAID-5 set. It's mounted as /home and all of our stuff live
sin there.



The remaining 20Gb of space on disk 3 was originally swap, and I left the
20Gb of space on disks 4 and 5 unused.



I then added an additional Two 500Gb Spinpoints. - I created 20Gb
partitions
on these and built a  60gb RAID-5 set out of the partitions on disks 3-6.



More interesting is what I did with the "big" partitions - I
created a 480Gb
partition on each of the new drives, then added these partitions into the
big RAID-5 set. Initially they are added as hot swap disks, however the
mdadm software allows you to dynamically rebuild/reshape the array out to
use the whole space - which took about 17 hours. I was then able to expand
the ext2 partition to bring my /home space up to 2.3Tb



Although I have not had to weather a physical drive failure yet, I *have*
simulated one - the mdadm software allows you to fail a disk out of the set
(I failed disk 3), which can then be unplugged from the system.



There's a noticeable degradation of performance, but it runs - and is easy
enough to re-integrate the disk (took about an hour).



I can't speak highly enough about the mdadm software - and the fact that
it's free is jaw dropping.



Ian.







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