fsarchiver

http://www.fsarchiver.org/Main_Page

It's a filesystem imaging program, like a more advanced version of partimage. One of its more interesting featuers is that you can force it to do a hot backup of an RW-mounted filesystem.

Is this a good idea? Probably not. Definitely not in production environments. However, I will also note that fsarchiver checksums every file it copies. So if it does fail to preserve a file, it will at least tell you that the file failed to copy... For whatever that's worth.

That being said, I was able to take a hot backup of my Debian laptop's root partition (while mounted RW - no files failed) and restore it successfully on another computer. Yay.

That being said, if you must do hot backups on UNIX, you should probably stick with tar or cpio anyway; those will offer you more flexibility. Unless you're using ACLs or something.

 

Not true.
If the FS or underlying storage supports snapshot, such as LVM, then its totally safe.

Without anyway to freeze the FS state (e.g. readonly or snapshot), the problem is that the FS can change whilst backing up, you can't guarantee the consistency of the entire FS.

In a controllable environment you will vastly increase the chances of not having problems (but IMHO still not trustworthy ).

tar, cpio still suffer the issues I have mentioned on a RW FS.

Cheers, Nick

 

FSArchiver is part of my tool set. I use it primarily from a SystemRescueCd. My favorite feature is being able to restore to a different file system that what was backed up. Also being able to restore to a smaller or larger partition is a plus.

 

Eww. Is there any reliable hot backup method for Linux at all? Aside from LVM (which has serious issues and limitations) and BTRFS (which is insanely slow and not anywhere near production ready)?

 

I'm not aware of a reliable hot backup method.

For what it's worth, I backup may root partition with Clonezilla every now and then, and my home partition regularly with the script presented in post #8 of this old thread.