Is it possible to resize software RAID5 with ReiserFS?

I have Understood that it is not possible to resize raid5. Will it be
possible via this little trick?

I have three partitions in raid5 (hda7, sda7, sdb7). If I just resize one
partition (say sdb7) and then restart my computer that partition will not be
on the raid after that, am I right? After that I could make "raidhotadd" and
it will restore sdb7 to my raid5. Will that result an error if the partition
is smaller than partitions already in use?

(ex. hda7 and sda7 are in use each with size of 110Gt, and I will raidhotadd
new partition with size of 25Gt. At the moment there is only 45Gt of stuff
on the raid)

If hotadding will work then there should come up raid5 with 50Gt of usable
space, right? After it has been restored I will make same thing with sda7
and wait for restoring of raid to finish. Finally with hda7 and will have
smaller raid5. Will this work?

Reason for doing this is the faster speed of harddisk in the start of disks
(I have 3x120Gt disk). I will store a lot of big files (video files) and it
might be good idea to store these files at the end of disks and keep system
files and home directories on the faster part of disk. I know it would slow
down if I handle video files at the same than doing something else because
the head of disk would move between middle and the end of disk depending
which file is in use. That is not common situation.. If I handle video files
then I would do nothing else and vice versa.

Disks are partitioned identically (sda1 and sdb1 are backups of hda1)
__________________________________________________ ___________
| raid0 raid5 raid5 |
| boot | swap | /tmp | system and | video files |
| small | 1G | 7Gt | home dirs, 25Gt/disk | 87Gt/disk |
|_________________________________________________ ____________

compared to
__________________________________________________ ___________
| raid0 raid5 |
| boot | swap | /tmp | system, video files and |
| small | 1G | 7Gt | home dirs, 112Gt/disk |
|_________________________________________________ ____________

If this good idea or not?

ps. I have tested empty disks (all of them are same type only connection
differs, pata vs. sata) and the last third of disks really is slower.

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Matti Kleemola wrote:
>
> I have Understood that it is not possible to resize raid5. Will it be
> possible via this little trick?

See raidreconf(8)

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Raimo Koski raimo.koski at raimokoski.com http://www.raimokoski.com/