change SCSI id's of drive in peripheral bay? bscott at
Fri Dec 20 14:58:00 CST 2002

On Fri, 20 Dec 2002, at 2:27pm, alazarev at wrote:
> 1/2 backplane + 1/2 peripheral on the 1st RAID channel
> 1/2 backplane + 1/2 peripheral on the 2nd RAID channel

  That is fine and reasonable, with (again) the possible exception of the
peripheral bay.  Do you have a hotswap cage installed, or is it just a
couple of drives with cables hanging off each one?

  I will assume it does not have a hotswap cage.

  You will need two SCSI cables.  Each one needs three connectors on it.  
No terminators should be on the cables.

  You should find that the main hotswap cage (the one with eight drives) has
two SCSI connectors on the backplane.  One end of each cable will attach to
one of those connectors (one cable per connector).  The middle connector on
each cable will attach to one of the drives in the peripheral bay. The other
end of each cable will attach to a channel port on the RAID controller.

  The main hotswap cage will automatically split the backplane when you have
things attached to both connectors.  Termination will be done in the
controller and in the backplane of the main hotswap cage.

  You should then be able to go into the MegaRAID BIOS utility at boot and
create your logical volumes spanning the two channels.  (The PERC/?C
controllers are re-branded MegaRAID cards.)

  Since the MegaRAID controller, in theory, supports drive roaming, you
might even be able to preserve existing logical volumes while doing this.  
I would not bet on it, though.  Have a backup -- correction: Have several
backups, and test them, before you try this.

Ben Scott <bscott at>
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