Joerg Steffens
7f8ddf96a2
It is important to be able to access tape changer ("Medium Changers") by
persistant name.
While tape devices can be accessed via /dev/tape/by-id/ and
/dev/tape/by-path/, tape-changers could only be accessed by
/dev/tape/by-id/.
However, in some cases, especially when accessing Amazon Webservice
Storage Gateway VTLs (or accessing iSCSI VTLs in general?) this does not
work, as all tape devices and the tape changer have the same ENV{ID_SERIAL}.
The results is, that only the last device is available in
/dev/tape/by-id/, as the former devices have been overwritten.
As this behavior is hard to change without breaking consistentcy,
this additional device in /dev/tape/by-path/ can be used to access the medium changes.
The tape devices can also be accessed by this path.
The content of the directory will now look like:
# SCSI tape device, rewind (unchanged)
/dev/tape/by-path/$env{ID_PATH} -> ../../st*
# SCSI tape device, no-rewind (unchanged)
/dev/tape/by-path/$env{ID_PATH}-nst -> ../../nst*
# SCSI tape changer device (newly added)
/dev/tape/by-path/$env{ID_PATH}-changer -> ../../sg*
Tape devices and tape changer have different ID_PATHs.
SCSI tape changer get the suffix "-changer"
to make them better distinguishable from tape devices.
systemd - System and Service Manager
Details
General information about systemd can be found in the systemd Wiki.
Information about build requirements are provided in the README file.
Consult our NEWS file for information about what's new in the most recent systemd versions.
Please see the HACKING file for information how to hack on systemd and test your modifications.
Please see our Contribution Guidelines for more information about filing GitHub Issues and posting GitHub Pull Requests.
When preparing patches for systemd, please follow our Coding Style Guidelines.
If you are looking for support, please contact our mailing list or join our IRC channel.