Incremental backups with Xtrabackup and other strange things


I was experimenting with the Xtrabackup tool, hoping to get incremental backups working finally. This is on Ubuntu 10.10 with Percona’s 5.1.55-rel12.6-log running full innodb databases. Xtrabackup version 1.4-193.

I believe I have it working, however, some bizarre output is being displayed during the backup process.

Here’s what I’m running:

innobackupex-1.5.1 --defaults-file=/etc/mysql/.my1.cnf /media/host_share/backups/

The above creates a full backup with the defaults-file having extra information that shouldn’t be accessible (ps aux etc…) like login info

This creates a directory of about 2GB, consistent with the ib* files in the mysql datadir.

I then insert 3 records into 1 table and then run an incremental with the following command:

xtrabackup --backup --defaults-file=/etc/mysql/.my1.cnf --target-dir=/media/host_share/backups/2011-04-12_10-55-54/incremental1 --incremental-basedir=/media/host_share/backups/2011-04-12_10-55-54/

The output has several “>> log scanned up to (2630529288)” lines and the incremental backup of files with three rows takes 97 seconds!

Final output is:

xtrabackup: The latest check point (for incremental): ‘2630529288’>> log scanned up to (2630529288)xtrabackup: Stopping log copying thread.xtrabackup: Transaction log of lsn (2630529288) to (2630529288) was copied.Elapsed time: 97 seconds.

The contents of /media/host_share/backups/2011-04-12_10-55-54/incremental1 are three files:

-rwxrwxrwx 1 root root 144K 2011-04-12 13:43 1 root root 68 2011-04-12 13:45 xtrabackup_checkpoints-rwxrwxrwx 1 root root 2.5K 2011-04-12 13:43 xtrabackup_logfile

I then decided to take a 2nd full backup which started also showing several lines with “log scanned up to…” abd the backup took around 60 seconds longer than the first one did.

I know that MySQL’s Enterprise Backup (innobackup?) has an atoi() bug with large LSNs but that completely stops the incremental backup from occurring (, is something similar here occurring or is this something that I have to live with?

Thank you.

What is the bizarre output? Nothing you posted looks wrong to me. I don’t think there is any bug, rather, there is a performance problem (which we might consider to be a bug) in that xtrabackup will visit every page in the database and check its LSN to determine whether it has changed since the last backup. That simply takes a while. We’re going to introduce a new way of doing incrementals in the future which will avoid this.

Thanks for your reply :slight_smile:

What I meant by bizarre was the repeated “>> log scanned up to (2630529288)” statements displayed on the console and I was worried that I was hitting something related to what I observed in the Enterprise Backup tool. If that output corresponds to the page checks and is expected, then all is well, though I do wish it were just a little faster on the incremental backups and I wait for any updates impatiently :smiley:

Thanks again!


That output is normal. I’ve added a sample of it to the documentation. Thanks!