Support for advanced filesystem features (setuid/setgid/xattrr/hardlinks/sockets, etc)

[mbiebl]

Version: 0.6.1

Followup to #543

# ls -al /usr/bin/sudo
-rwsr-xr-x 1 root root 147560 Feb  2  2020 /usr/bin/sudo

After the kopia restore

# ls -al /var/tmp/restore/sudo
-rwxr-xr-x 1 root root 147560 Feb  2  2020 /var/tmp/restore/sudo

I assume aside from the SUID bit, SGID and sticky bit are also not (yet) properly supported.

[jkowalski]

Yes, there's a whole bunch of things currently not captured at the filesystem level, including setuid/gid, hardlinks, mount points, sockets, xattr, ACLs, etc.

Currently only files (simple, without alternate streams) and symlinks are supported, and only simple filemode + owner/group are supported.

I'm going to repurpose this issue to track adding the missing pieces and close the others as duplicates.

[mbiebl]

Sounds fine to me, thanks. Wasn't sure if you preferred individual issues or not.

[mbiebl]

Currently only files (simple, without alternate streams) and symlinks are supported

Hm, see #543. When running kopia restore, no symlinks were restored. Browsing the repository via kopia-ui though, I see those files.

[JimW-MC]

Ideally this will include - under Windows - support for:

• File attributes
• ACLs
• Symlinks (file & folder), Junction points & Hard links.

IMO, for the latter, the required behaviour should be to just capture the symlink/junction point/hard link itself, and not it's target.
If there really is a need to capture the target (or more accurately the target's content), then that could be handled with an optional - non default - argument.

[WMP]

If you write this feature kopia will be good tool to backup whole VM, now i can do this with xfs_dump tool.

[dima-altinity]

@jkowalski
very interesting project and I also think that this feature is really missing.
whats the current status of symlinks and hardlinks support?

[jkowalski]

Symlinks and hardlinks are correctly backed up. Both can be restored but hardlinks are restored as individual files and not as hardlinks.

[dima-altinity]

thnx @jkowalski , just would like to clarify how does it work( restore) if there are mutliply hard links to the same file?
lets say I have file /home/user/1.tar.gz ( size 1Gb) and /home/user/link1.gz, /home/user/link2.gz that are hard links to /home/user/1.tar.gz
Scenarios

1. I create and upload backup to S3 for /home/user/ ( how much data will be sent and stored on S3 - 1Gb or 3Gb ?)
2. I create /home/user/link3.gz hardlink that points to the same file /home/user/1.tar.gz. Then upload backup to S3. How much data will sent to S3 during this operation?
3. I restore backup from S3 to local ( backup contains 1 file and 3 hard links). How much data will be downloaded from S3? 1Gb or 4Gb?
4. do I understand right that after restore this backup I'll get 4 files in /home/user/ with total size 4Gb ?

[jkowalski]

1. 1gb because of deduplication
2. 0 (plus minimal overhead for indices and manifests)
3. Physically 1 gb will be downloaded (because of caching) but logically each copy will be independently fetched (so 3gb).
4. That is correct.