XFS and loss of data when power goes down

Question

Each time electricity goes down, my desktop (without UPS) loses some temporary information.

• Opera can lose settings, history, cache, or mail accounts (Thanks heavens I was wise to use IMAP). Partially or all together.
• a whole file (complete and save) in Geany appeared empty (and I didn't commit it to Git)
• rhythmbox lost all podcasts subscription data

I'm afraid there are other losses I just didn't see.

What's the reason? A memory files cache, a mem-disk? Or non-atomic file writes in xfs? I have Ubuntu 9.10 and XFS on both / and /home partitions.

Is ext4 safer in such circumstances? I've seen ext3 is faster. Is it as safe as *4?

Given that the apartment I rent is connected to a common bus and 1 safety switch for several apartments, and the neighbors - alone or together - overload it at least once every week, the lights go down often enough for this to be an issue.

Answer 1

XFS is not a journaling filesystem, such as ext3 and ext4. So, files are overwritten in place, instead of copied, the new one modified and then the file pointer moved from old to new (over-simplifying things a bit).

As a result, you are more likely to lose data, end up with outdated data, or end up with a truncated file with XFS.

Given your lack of control of the situation, you are a good candidate for buying a small UPS.