Filesystem Backup should be abot to ignore TAR error "File changed as we read it"

Submitted by Locutus on Thu, 05/26/2011 - 13:57

I'm creating backups of a Minecraft server installation using Webmin's Filesystem Backup feature.

MC has a "stop doing data file updates" mode - hence I don't shut down the server during backup. Problem though is that MC still does some access to some of its directories in that mode. The result is:

Performing backup of /home/minecraft to /backup/minecraft.tgz ..
 
tar: Removing leading `/' from member names
tar: /home/minecraft/server/skylands: file changed as we read it
tar: /home/minecraft/server/dune: file changed as we read it
tar: /home/minecraft/server/warwick: file changed as we read it
tar: /home/minecraft/server/wondercraft: file changed as we read it
tar: /home/minecraft/server/gaia: file changed as we read it
tar: /home/minecraft/server/bordertest: file changed as we read it
.. backup failed!

All those "files" are actually map directories. I verified the resulting backup file as complete and correct. So those "errors" thus should be ignorable by Webmin and not be interpreted as a failure. A backup option "Ignore file changes during backup" might be a good way to go.

(The title of this issue was supposed to read "...should be ABLE to ignore". Can't edit to fix it unfortunately.)

Status: 
Closed (fixed)

Comments

Submitted by JamieCameron on Thu, 05/26/2011 - 16:33

I've seen this on my own system when backing up /etc/webmin - Unfortunately the tar command has no option to ignore this error, which is pretty much bogus in my opinion. However, it does have an option to ignore all read errors including this .. so in the next Webmin release, I will add an option to skip read errors when backing up.

Submitted by Locutus on Fri, 05/27/2011 - 08:04

Okidoki! Will we still get errors in case something seriously fails with the backup then? I wouldn't want to not be notified if the backup doesn't work for weeks due to full target disk or something. ;)

Submitted by andreychek on Fri, 05/27/2011 - 10:27

You would get a notice so long as it's not related to a read error :-)

Since tar can't distinguish between different types of read errors, anything that causes tar to not be able to read a file would be ignored in this case (which likely includes a disk error).

I believe Jamie is using tar's "--ignore-failed-read" option if you wanted to read up on how that works.

But yes, all other errors, you would still be notified about.

Submitted by Locutus on Fri, 05/27/2011 - 10:56

Okay that's good. I suppose we don't really need to be informed about disk errors while making backups. If the disk had errors to begin with, it doesn't really matter if those get backed up or not. :) To scan for errors, a regular fsck is probably more appropriate.

Submitted by Issues on Sat, 06/11/2011 - 13:23

Automatically closed -- issue fixed for 2 weeks with no activity.