Determine OCFS2 Version

Question

Hi all,
First off I'm not sure this is the best section so forgive me.
We've got several OCFS2 1.4 clusters that have started getting the "No Space Left on Device" error. The solution is to upgrade to OCFS 1.6. I've installed UEK and backed up the device.
What I would like to know is how can I determine with which version of OCFS2 a device was formatted? I've looked at all usual suspects (tunefs, debugfs etc) but am coming up blank.
Any ideas? I just want to make sure that all troublesome devices are formatted with OCFS2 1.6 and not still using 1.4
Cheers,
Pedro

Answer 1

Take what follows with a grain of salt; I am not an OCFS2 maintainer.
What I would like to know is how can I determine with which version of OCFS2 a device was formatted?Sorry, but that is not the question that should be asked. Instead, think of OCFS2 as a baseline feature set plus some optional extension features.
Regardless of which version of the tools does the actual formatting, the on-disk format is the same. The optional extension features are packaged into metadata that are incomprehensible to incompatible OCFS2 drivers and tools; all these tools know is the file system has some features that are not understood, and thus access to the file system is denied.
The mkfs.ocfs2(8) man page lists the available options and their associated feature level.
The on-disk file system format is the same; check the OCFS2 FAQ about "rolling upgrades" to see which versions have the same on-disk format. If a rolling upgrade is possible, the on-disk format is upwardly compatible. Even for versions where a rolling upgrade is not possible, it is usually because the intra-node communications protocol differs and not because the on-disk format changes. The FAQ should mention whether or not a dump and restore is required.
With all this in hand, the right question is: what optional features does my file system use -- a question best answered by the tunefs.ocfs2(8) command:
# tunefs.ocfs2 -Q "Label: %V\Features: %H %O\n" /dev/sdg1Obviously, a pristine 1.4 file system would pose no issue here, but you can install the newer 1.6 tools and check for yourself.
FYI: Your original problem was getting an out of space notice and you have observed the fix is implemented in version 1.6 and is not available in prior versions. The changes made were too widespread for backporting, but the changes were all contained in the driver and tools level; there were no on-disk format changes were needed.