3ware 9000 Series SATA Raid and Fedora Core 2 ?

[James Wilkinson]

Robert Burton wrote:
> So do you think i would be better off with Fedora Core 3 test 2?

If you want RAID 5 to protect your data. No. It's not ready for that
yet.

I had Rawhide corrupt an ext3 partition a while back. You have to
expect that sort of thing might happen occasionally when running test
versions: the developers go and do something unreasonable like putting
in new code to see if it works or not.

> I plan on using three disk in RAID 5. Is it possible to "convert"
> drive that is not mirrored to a RAID 5? I'm sure you could do this
> with mirroring. But what if I did as you suggest and update the OS and
> them want to go RAID 5?

I'm sure that, in theory, it would be possible to write such a program.

One could even "wing it" with the existing tools IF one could manage to
create a RAID 5 logical partition with one disk missing: one would treat
each filesystem on the existing disk as one partition, and simply copy
all the data onto the RAID 5 logical partition. Then one would check
that the RAID 5 could boot, and run the tools to add the existing disk
as the missing disk of the new RAID5 set. Wait a *lot* of time for all
the redundancy information to be written to the right place, and Bob's
your relative of choice.

If one wanted to do the same thing with an existing disk that was
mirrored, one would "break the mirror" (remove one disk from the mirror)
and do much the same thing.

You see, RAID 5 stripes data and the redundancy data over all three
drives: any file [1] above three RAID block sizes will have data on all
three disks. It's not as simple as just adding more space to the thing.

ASCII graphics warning: you'll need a fixed size font.

  Disk 1              Disk 2             Disk 3
 +---------------+   +---------------+  +---------------+
 |Data block 1   |   |Data block 2   |  |Redundancy data|
 |Redundancy data|   |Data block 3   |  |Data block 4   |
 |Data block 5   |   |Redundancy data|  |Data block 6   |
 |Data block 7   |   |Data block 8   |  |Redundancy data|

...

I'd strongly recommend good backups in any case.

But I think you'll have to back up, create the new disk stucture, and
restore.

Unless anyone knows differently?

James.

-- 
E-mail address: james | "My aunt's camel has fallen in the mirage."
@westexe.demon.co.uk  |     -- "Soul Music", Terry Pratchett.