Backups to HFS+ Drives
The proprietary MacOSX HFS+ disk format, although popular among many GMCA users,
is considered as "probably
the worst file-system ever" (Linus Torvalds) and has a restricted support under Linux. Therefore GM/CA purchased a proprietary commercial HFS+
driver for Linux by Paragon
Software. This driver is installed on the second day-workstations ws4, ws5, and ws7 only and working with
HFS+ disks connected to these computers does not require any additional steps.
Note: connecting USB3 drives to USB3 ports is strongly
advised. Not all USB ports on the workstations are USB3; look at the labels
or ask your host.
Additional Information
For the latest changes with the backup procedures and detailed technical
instructions please refer the Backup Manual
(PDF).
Mounting HFS+ on Linux with open-source driver
Information below is for users who wish to use other GM/CA
workstations (NOT ws4, ws5, or ws7) to write data to HFS+ with the help of
open-source
kmod-hfsplus Linux driver. We do not support it; so use it on your own
risk.
The kmod-hfsplus driver can read any HFS+ drives, but for
writing the HFS+ journal must be temporarily disabled. Journal is a log
recording the intentions of file system changes before they are
committed. Let say, you are copying a file. The file system index is
updated once copying is complete while the journal (the log) is updated
as soon as the copying starts. It may provide better filesystem recovery
in case of unsafe disconnect or sudden power loss. For those who are
interested in additional details, please consult the following
Wikipedia article.
The journal on an external HFS+ drive can be disabled either under
MacOSX or directly under Linux once you connect the drive to the USB port of any
GMCA workstation. The precondition is that the drive is not used by Apple's Time
Machine software. To disable the journal under MacOSX, hook the drive to any Mac,
then start Disk Utility, unmount the volume and click on the "Disable Journaling"
button in the File menu.
To disable the HFS+ journal under Linux, hook the drive to available
GMCA workstation (ws1 to ws7), open a terminal and run the "mount" command. Look
at the command output and find the device corresponding to the HFS+ drive. For example,
let it be /dev/sdb1. If the output shows that the drive is mounted read-only
(ro), then it means that the driver detected an active HFS+ journal. In this case
do "safe disconnect" to unmount the drive and run:
sudo disable_hfsplus_journal /dev/sdb1
If you have any concerns about the health of HFS+ filesystem,
you can run the file system check before disabling the journal:
sudo fsck.hfsplus /dev/sdb1
Now remount the drive (unmount it using "safe disconnect",
then unplug and plugin back again) and verify that it is mounted read-write
by running the "mount" command again.
The rest of the operations with the drive, i.e. running rsync, is
the same as usually. Once you are done with the backup, unmount the drive using
"safe disconnect". Do not forget to turn the journal back on. To do that, hook
the drive to any MacOSX computer, then start Disk Utility, select the drive
and click on the "Enable Journaling" button.
Possible Limitations
- The drive is being used with the Apple Time Machine. You can disable using
an external drive as a Time Machine backup by hooking it to your Mac and launching
the Time Machine application.
- The drive is larger than 2TB. In the past this could lead to the file system
corruption on the drive. We do not know if this problem is solved in the current
version of the driver.
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