[Discuss] Disk numbering

[gaf at blu.org (Jerry Feldman)]

On 10/05/2011 12:25 PM, Bill Bogstad wrote:
> This isn't a reply to any particular message on this thread, but I
> haven't seen anyone mention the /dev/disk directory yet.   On my
> Ubuntu systems, it contains  subdirectories by-uuid, by-label,
> by-path, etc.  Those sub-directories contain symlinks to the more
> traditional sd or mapper names for drives.   I assume this is done by
> udev or something so it might not be usable in early boot scripts, but
> it can certainly be used for anything run after the system is fully
> booted.   Admittedly, those symlinks are relative which makes things
> ugly, but readlink solves that problem.  For example,
>
> readlink -e /dev/disk/by-label/os_part
>
> returns
>
> /dev/sda6
>
> on one of my systems.
>
> Judicious labeling of the partitions with human recognizable names is
> in my opinion even better then static sd* names.
>
> This doesn't solve the problem of actually figuring out which physical
> drive is actually sda vs sdc.  I've been forced to eject CD drives (in
> systems with more then one), force artificially high IO rates (using
> per-drive activity LEDs), or seek rates (detected by vibration) to do
> so in the past.  There is a possibility that the by-path subdirectory
> (which refers to buses/slots) might help in this regard, but I don't
> have any experience to confirm this.
RHEL also has /dev/disk as does Fedora.

-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
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