Re: Changing controllers strategy?

[Theo Van Dinter]

On Tue, Mar 28, 2000 at 12:47:08PM -0500, Seth Vidal wrote:
> > I'm a bit cautious here as I've had a bad experience when experimenting
> > with disk changing  and ended up with a corrupted array.

Is it just me, or should the RAID superblock include information to make disk
ordering unimportant?

BTW: worst case (Assuming RAID 4/5), you can fail one partition, move it to
the new controller/new name, then add it back.  repeat as necessary.

-- 
Randomly Generated Tagline:
I don't know if it's what you want, but it's what you get.  :-)
  -- Larry Wall in <[EMAIL PROTECTED]>

Re: Changing controllers strategy?

[Piete Brooks]

> I've got a four disk RAID5 setup on one controller. I want to add
> another controller, but am unsure of what strategy  I should adopt to
> maintain the RAID  integrity.

You didn't mention which raid kernel code you are using.

If it is recent, each partition will have `Persistent Super Block's which
include info about all the RAID devices and which device this is.
The result is that you can change a disk's ID, and the RAID system will
automatically adjust it for the new configuration.

Re: Changing controllers strategy?

[Seth Vidal]

> I've got a four disk RAID5 setup on one controller. I want to add
> another controller, but am unsure of what strategy  I should adopt to
> maintain the RAID  integrity.
> 
> As the order that the disks are found and  identified as sda, sdb etc.
> determines the RAID structure and depends on the disk ID's, how do I
> maintain this when I put two of them on a different controller  with
> different ID's.
> 
> I'm a bit cautious here as I've had a bad experience when experimenting
> with disk changing  and ended up with a corrupted array.
> 
> It would be nice if Jacob's great HOWTO included this sort of info and
> also how to recover a snarled up array.
> 

I'd do this:

take the highest scsi id numbers of your drives and put them (unchanged)
on the new controller which should be SECOND in the module load and pci
load sequence.

the linux will look at the drives like this:
scsi_hostadapter0
/dev/sda
/dev/sdb

scsi_hostadapter1
/dev/sdc
/dev/sdd

If I'm wrong here someone please correct me.

thanks


-sv

Changing controllers strategy?

[Jim Ford]

Hi

I've got a four disk RAID5 setup on one controller. I want to add
another controller, but am unsure of what strategy  I should adopt to
maintain the RAID  integrity.

As the order that the disks are found and  identified as sda, sdb etc.
determines the RAID structure and depends on the disk ID's, how do I
maintain this when I put two of them on a different controller  with
different ID's.

I'm a bit cautious here as I've had a bad experience when experimenting
with disk changing  and ended up with a corrupted array.

It would be nice if Jacob's great HOWTO included this sort of info and
also how to recover a snarled up array.

Regards: Jim Ford