[dm-devel] Does dm handle tape devices?

[lemons_terry at emc.com]

Hi

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.

tl

-----Original Message-----
From: dm-devel-bounces at redhat.com [mailto:dm-devel-bounces at 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 at emc.com <lemons_terry at 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
environment.

-andmike
--
Michael Anderson
andmike at linux.vnet.ibm.com

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