[dm-devel] Does dm handle tape devices?
Phillip Susi
psusi at cfl.rr.com
Mon Nov 5 22:23:56 UTC 2007
lemons_terry at 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.
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