Backup doesn't complete

Hi,

I’ve tried to backup my site http://anahicastro.com with BackWPup Scheduler. The site is a network, with the original site hosted in the root directory and two other WP sites hosted respectively in directories /es and /en (original site is in French, the other two in Spanish and English). My hosting provider is Strato.

It’s the first time I use this plugin, so I tried to backup the whole network from the root site. Either with the default parameters or changing them, the backup starts, then seems to encounter a problem and go backward a stage, then proceeds until it stops again, and this process is repeated indefinitely. I get the message:

The ZIP creation is in progress (0/0 files has been added in 12 zip files and the current size of the zip files is 50.07 MB).

Please wait, a backup is in progress for 20 seconds! Wait until 45 seconds for an automatic restart.
This error message may also be generated if the chunk size is too big: try first to set the chunk size to 1Mo in order to avoid any memory saturation of your server and then increase it slowly…

So, I’ve set the chunk size to everything from 1 to 50 Mo, and no change. It extracts all the data from the database and starts creating zip archives, then at some point it shows this message (the number of files, zip archives and total Mo varies depending on the chosen chunk size), then it resumes zip creation, and again the message and a stage backwards. Like, it encounters the first problem when it reaches 60 Mo, then when it resumes work it says total size so far is 30 Mo, then again 40… etc.

Can you help? I couldn’t find any answer to this specific problem anywhere.

http://wordpress.org/plugins/backwpup/