Bacula配置后lsscsi无法识别Dell TL4000光纤磁带库changer

Let’s walk through the most likely causes and actionable fixes for this issue:

1. Check for Stale Bacula Processes Holding the Changer Device #

When you exit bconsole, it’s possible the Bacula Storage Daemon (bacula-sd) hasn’t properly released the mediumx device handle. Here’s how to verify and fix this:

• Run lsof /dev/mediumx or fuser /dev/mediumx to see if any processes are still attached to the changer device.
• If you spot Bacula-related processes, stop the storage daemon gracefully first:

  systemctl stop bacula-sd  # For systemd-based systems
  # Or service bacula-sd stop for init.d systems
  

  If the process won’t stop, use kill <PID> to terminate the stuck process directly.
• After stopping the process, re-run lsscsi to check if the mediumx device reappears.

2. Verify Device Permissions and Group Ownership #

Bacula runs under a dedicated bacula user, and incorrect permissions on the mediumx device can make it "invisible" after Bacula accesses it:

• Check current permissions with:

  ls -l /dev/mediumx
  

  The device should ideally be owned by the bacula user/group (or tape group) with permissions like crw-rw----.
• If permissions are wrong, create a udev rule to set ownership automatically:
  1. Create a file like /etc/udev/rules.d/99-bacula-tape.rules with:

     SUBSYSTEM=="scsi_generic", ATTRS{model}=="TL4000", OWNER="bacula", GROUP="bacula", MODE="0660"
     

  2. Reload udev rules and trigger a rescan:

     udevadm control --reload-rules
     udevadm trigger
     

3. Validate Bacula Storage Daemon Configuration #

Misconfigurations in bacula-sd.conf can lead to improper device handling:

• Open your bacula-sd.conf and check the autochanger definition:

  Autochanger {
    Name = TL4000-Changer
    Device = Drive-0, Drive-1
    ChangerDevice = /dev/mediumx
    ChangerCommand = "/usr/sbin/mtx-changer %c %o %S %a %d"
    AutoChanger = yes
  }
  

  Ensure ChangerDevice points to the correct /dev/mediumx path, and AutoChanger is set to yes.
• Restart the storage daemon after making changes:

  systemctl restart bacula-sd
  

  Then test again by entering/exiting bconsole and running lsscsi.

4. Unlock the SCSI Changer Device #

Some SCSI devices get locked by processes, preventing them from being listed by lsscsi. Use the sg3_utils toolset to unlock it:

• Install sg3_utils if missing:

  apt install sg3_utils  # Debian/Ubuntu
  yum install sg3_utils  # RHEL/CentOS
  

• Run the unlock command:

  sg_unlock /dev/mediumx
  

  Re-run lsscsi to check if the device reappears.

5. Check System Logs for SCSI Errors #

System logs may reveal why the device is disappearing:

• Check dmesg for SCSI-related issues:

  dmesg | grep -i scsi
  dmesg | grep mediumx
  

  Look for errors like "device disconnected" or "I/O error".
• Also check /var/log/messages or /var/log/syslog for Bacula-specific errors that might point to communication issues with the changer.

内容的提问来源于stack exchange，提问作者Brosig