Hi Patrice,
You always get that message at the start of a backup using WPB2D. The memory limit is fine, but I think you’d want the time limit increased.
I might be barking up the wrong tree but my understanding is, if there is a pause in the operation for 30sec or more then effectively this is seen as a timeout, and the backup operation will fail to complete (and start again. Then possibly fail again. Then start again. Rinse and repeat). The plugin itself tries to modify these settings (I believe to 360sec and 128M) but it looks as though in your case it is unable to do this.
Depending on your host you may be able to edit this configuration yourself, by editing the php.ini file located in the root of your web folder. Having said that, considering the plugin wasn’t able to auto adjust these settings, you might find you can’t manually do it either.
You could therefore ask your host to modify it for you, to 360sec and 128M (I’ve seen it set higher than this, but the above is what the plugin tries to do, so I’d start with that).
If on the other hand you are seeing no issues with your backup, then there’s no need to change the settings. However your website is presumably getting bigger every day as you add blogs, more images, etc so if it was my site, I’d want the time limit increased.
Hope that helps!