swapping external hard drives

[Scott Mitchell]

On Fri, Jan 02, 2004 at 02:55:47PM -0600, Dan Nelson wrote:
> In the last episode (Jan 02), Toomas Aas said:
> > However, when I umount /backup and remove the drive, the da0 device
> > somehow remains active (can be seen with 'camcontrol devlist'). When
> > I then plug in the second drive, it becomes da1, which spoils all my
> > beautiful backup plans. I would prefer that when I remove one drive
> > and plug in the other, it becomes da0 again. So I need to get the
> > 'old' da0 entry to go away when unplugging the drive. How can I do
> > that?
> > 
> > I tried 'camcontrol rescan 0:0:0' after disconnecting the drive, but
> > it just hangs until I plug the drive back in. I tried 'camcontrol
> > reset 0', but this returned error 0x6 (IIRC).
> 
> Try just "camcontrol rescan 0" to rescan the entire FW bus.  I don't
> know if scanning just a single LUN will allow the whole device to
> disappear.  I think it was more intended for SCSI/FC RAIDs, so you
> could add/remove/resize volumes.  Just guessing here, though.

You probably also want to do 'fwcontrol -r' a few times after unplugging
the drive (three seems to work for me...)  See sbp(4) for reasons why this
is necessary.

Also note the warning about tagged queueing on that page - hopefully you
lucked out and your drives are OK with this; I had serious file corruption
issues until I turned off tagged queueing.  You might want to verify that
the data on the backup is really what it should be :-(

	Scott

-- 
===========================================================================
Scott Mitchell           | PGP Key ID | "Eagles may soar, but weasels
Cambridge, England       | 0x54B171B9 |  don't get sucked into jet engines"
scott at fishballoon.org | 0xAA775B8B |      -- Anon