Is it safe to directory backup (tar) attachments while Confluence / JIRA are on?

[Jiri Pik]

I have a huge Confluence / JIRA installations with tens of gigabytes of attachments. 

Backing them up takes a long time. The command is, for example,

call(['/bin/tar', '-zcvf', attachments_backup_filename ,'/var/atlassian/application-data/confluence/attachments'])

(1) Is it safe to run this command while Confluence / JIRA are running to maintain the maximum availability?

(2) What is the worst which can happen?

(3) Should I add some additional parameters to the above "tar" command to make it more thread safe?

[Nic Brough -Adaptavist- · Accepted solution]

It is safe to do this while Confluence is running, as you are just reading the files to create an archive.  It won't damage Confluence in any way.

The worst cases are that someone is uploading a new attachment in just the place the backup is running, so you only get part of that file backed up, or your backup locks a file while someone is trying to delete it, so confluence reports a failure to delete to the user.  I don;t think either of those are critical failures.