nodes stops working on timely matter.

Hello,

I am running a three node cluster and about every week one of the nodes randomly stops working.

I can see this in the log file: [url]http://pastebin.com/4ujRtCBW[/url]

Any idea how to fix it or how to add an alternate replication method in case the xtrabackup is failing as it can see in the logs?

thanks in advance.