user_xattr about ceph-container

[Ulexus]

Perhaps I'm blind (I haven't actually run the demo), but I don't see anything in there which requires extended attributes.

[leseb]

I'm not getting this one either...
@lorieri do you mean that the partition where Ceph will run need user_xattr and thus we should put this as a recommendation?
I believe then that this is not only valid for the demo but also the daemon and osd images.

[lorieri]

When I run the Demo following the instructions at docker hub it fails and shows a user_xattr error, re-mounting the partition make it works.

[leseb]

Hum never faced that problem before perhaps my fs has user_xattr enabled by default, can't tell.
Feel free to update the README :)

Thanks for reporting this @lorieri

[lorieri]

I'm afraid the remount could be dangerous, I'm not sure how to say it, but let me try :)

[Ulexus]

I don't know why extended attributes would be required. I can say for certain that none of my live Ceph systems have filesystems mounted with the user_xattr flag.

What storage backend are you using for Docker? Perhaps that is the issue? Do you know which component is requiring the extended attributes?

[lorieri]

Component: OSD

$ docker info
Containers: 159
Images: 1267
Storage Driver: devicemapper
...
 Pool Blocksize: 65.54 kB
 Backing Filesystem: extfs
 Data file: /dev/loop0
 Metadata file: /dev/loop1
...
 Udev Sync Supported: true
 Deferred Removal Enabled: false
 Data loop file: /var/lib/docker/devicemapper/devicemapper/data
 Metadata loop file: /var/lib/docker/devicemapper/devicemapper/metadata
 Library Version: 1.02.95-RHEL6 (2015-06-17)
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 2.6.32-504.el6.x86_64
Operating System: <unknown>
CPUs: 8
Total Memory: 23.47 GiB
...

[lorieri]

#150

[butonic]

hm ... according to http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=ea6633369458992241599c9d9ebadffaeddec164 user_xattr is enabled by default since 2011.

The problem is rather an issue with AUFS: moby/moby#6980 The only workaround seems to be to fall back to devicemapper, which is recommended anyway, see 2.7 Do not use the aufs storage driver (Scored)

At least here the tip did not help ...

[butonic]

better recommendations seem to be moby/moby#1070 (comment)

[Ulexus]

@butonic : Agreed, for many reasons. No one should be using the AUFS backend anymore, if at all possible. @lorieri , if that's the case for you, try another filesystem/backend.

[lorieri]

merged :)