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RE: [dm-devel] Does dm handle tape devices?


Thanks for the reply.  I have a customer who runs three tape-aware
applications in one Linux system.  Two of those applications use device
files (ex., dev/nst0) to access the tape devices, so the persistent
udev-created symbolic links in /dev/tape/by-id and /dev/generic/by-id
will work fine for those applications.

A third application, alas, uses SCSI IDs to refer to the tape devices.
I've been instructed to seek a persistent naming solution for this
application, too, one that (hopefully) won't require modification of the
application.  I started out looking at the QLogic FC HBA's persistence
capability, and saw that it functions at the target level within a
single HBA.  But I found that some vendors don't support this method of
persistence, opting instead to use device mapper.

Hope this is clear.


-----Original Message-----
From: dm-devel-bounces redhat com [mailto:dm-devel-bounces redhat com]
On Behalf Of Mike Anderson
Sent: Friday, November 02, 2007 3:51 PM
To: device-mapper development
Subject: Re: [dm-devel] Does dm handle tape devices?

lemons_terry emc com <lemons_terry emc com> wrote:
> Hi
> I need to provide persistent binding / persistent device naming for
tape devices in Linux environments.  Does device mapper provide some
facility for this, or is DM only for disk devices?

Device mapper is only for block devices.

I saw your similar question on the udev list. Is there some reason that
udev will not provide a id that you can use. If not you can alter the
udev rules (or add your own) to provide a persistent id for your

Michael Anderson
andmike linux vnet ibm com

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