2014-02-02 20:08:19

High latency of Hetzner backup servers

My server is located in a Hetzner computer center. The backups are done with duplicity and are running every night. The data is put on backupservers from Hetzner.

Sometimes a backup fails with the following (shortened) error:

BackendException: ssh connection to $backup_server failed: Error reading SSH protocol banner

Duplicity uses paramiko as a ssh backend. The timeout for the ssh banner is set in the file transport.py on line 363:

        self.banner_timeout = 15        # how long (seconds) to wait for the SSH banner

Setting the value to something higher (e.g. 120) can help. For an estimation try this:

time echo quit | sftp $backup_server

On this sunday evening I get an answer time from about 2 minutes. I adjusted my transport.py to this value and keep an eye on the logs the next days.

Posted by toerb | Permanent link | File under: hetzner, backup