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

[Phillip Susi <psusi cfl rr com>]

lemons_terry emc com wrote:
> 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.

Device mapper has nothing at all to do with persistent device names. 
Device mapper is a kernel device driver that creates virtual block 
devices with interesting mappings to underlying block devices, such as 
raid.  Device naming is handled by udev.