Re: SCSI Device Addresses
On Sat, Mar 01, 2008 at 11:00:01AM +0000, Steve Dobson wrote:
> On Sat, 2008-03-01 at 14:31 +1100, Hamish Moffatt wrote:
> > Doesn't udev assign constant sdN/hdN identifiers? It appears to look up
> > the drive serial number and attempt to do this.
>
> From what I've observed hdN is consistant. hda is *always*
> primary-master,
> hdd is secondary-slave, and so forth.
Actually I don't think that is true with our udev configuration. It
tries to keep the same ID assigned to the same physical disk, so if you
rearrange them they maintain their IDs, and hence your fstab still
works.
> > Also, if you run LVM or software RAID then you get static identifiers
> > out of those automatically, even with the underlying disks moving
> > around.
>
> Yes, but you need fixed physical device addresses to create the LVM or
> software RAID devices in the first place.
No you don't. LVM puts unique identifiers on each physical volume, and
will scan all disks to find them. It doesn't hardcode their locations
anywhere. I think software RAID can also do this.
Hamish
--
Hamish Moffatt VK3SB <hamish@debian.org> <hamish@cloud.net.au>
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