openSuSE and /dev/tape changes

Hummdis · 06-04-2008, 02:13 AM

Hi Folks,

Does anyone have details on when and why the SuSE team usurped the /dev/tape symbolic link standard and created the /dev/tape/ folder hierarchy?

When using tools like mt, the default device entry of /dev/tape is now causing problems because the device is now a directory. Previously, /dev/tape was a symlink to the default, non-rewinding tape device (i.e.: /dev/nst0).

Thanks!

jschiwal · 06-04-2008, 02:57 AM

The links are created by rules in /etc/udev/rules.d/60-persistant-storage-end.

You can use "mt -f <device>" or even alias the mt command in /etc/profile.local.

tim914 · 06-05-2008, 04:36 PM

Thanks, but that doesn't explain why it was done and what its purpose is (i.e.: easier device naming, better handling of 100 attached tape devices...). I know that some have assumed a udev thing, but it's not necessary for udev. It would be nice to know the purpose since it's not present in all distributions and even the distributions that include it config it differently.

Hummdis · 06-10-2008, 08:01 PM

After doing some testing it appears that both Fedora and openSuSE do the same process, however, it depends if you're using a SCSI tape device versus a USB tape device. As you can see from below, the output is different.

Fedora 7 with SCSI tape drives:

Code:

$ ls -lR /dev/tape
/dev/tape:
total 0
drwxr-xr-x 2 root root 100 2008-06-02 09:16 by-id
drwxr-xr-x 2 root root 200 2008-06-02 09:16 by-path

/dev/tape/by-id:
total 0
lrwxrwxrwx 1 root root  9 2008-06-02 09:16 scsi-20800460600176c31 -> ../../st1
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 scsi--nst -> ../../nst0
lrwxrwxrwx 1 root root  9 2008-06-02 09:16 scsi-SHP_DAT160_HU171200LE -> ../../st0

/dev/tape/by-path:
total 0
lrwxrwxrwx 1 root root  9 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:4:0-st -> ../../st0
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:4:0-sta -> ../../st0a
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:4:0-stl -> ../../st0l
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:4:0-stm -> ../../st0m
lrwxrwxrwx 1 root root  9 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:8:0-st -> ../../st1
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:8:0-sta -> ../../st1a
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:8:0-stl -> ../../st1l
lrwxrwxrwx 1 root root 10 2008-06-02 09:16 pci-0000:02:02.0-scsi-0:0:8:0-stm -> ../../st1m

Whereas openSuSE uses something like the following with USB tape drives:

Code:

# ls -lR /dev/tape
/dev/tape:
total 0
drwxr-xr-x 2 root root 60 2008-06-10 16:01 by-id

/dev/tape/by-id:
total 0
lrwxrwxrwx 1 root root 10 2008-06-10 16:01 scsi-1HP_C1537A_HU105329YD-nst -> ../../nst0

Therefore, the major question here is that because /dev/tape is a folder, is there any known issue to deleting the folder so that /dev/tape can be used as it was prior to SuSE 10?

Does anyone know why this was changed in the first place?