Hello, Guys. I would be glad to help you, but I wrote in this thread before that I can't reproduce this problem. I need more information. Recently I tried to reproduce it again. I've made such steps:
1. Installed Ubuntu 12x64 or Ubuntu 12x32. I checked both.
2. Installed Plesk 11.5.30 with last updates.
3. Configured Personal FTP repository for backup on server level. I used Filezilla's FTP server.
4. I set scheduled backup settings for server: daily backup with rotation = 5 and not empty prefix.
5. I created customer with subscription, logged in using customer's account and set the same settings for scheduled backup too.
6. I waited for 6 scheduled tasks executions (to see that rotation works).
7. Upgraded Plesk to 12.0.18.
8. Waited for scheduled tasks executions again. All tasks are completed and rotation works correctly. No errors in log, debug mode was turned ON.
9. I checked FTP access for FTP user of subscription and everything works.
10. I changed prefix to another one and rotation = 2 in scheduled backup settings.
11. I waited for scheduled backup execution again to check rotation and I saw that everything works. Backups begin to rotate after the 3-rd backup execution.
12. I upload more than 17 GB in httpdocs and wait for scheduled backup execution again. And it is completed without any errors. Now I have server and subscription's backup on FTP. Both files have size = 17.5 GB. Rotation works too.
NO RESULT. NO ERRORS IN LOGS. Everything works as expected.
My OS versions:
1. Ubuntu 12.04x32.
Linux version 3.2.0-24-generic-pae (buildd@vernadsky) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #39-Ubuntu SMP Mon May 21 18:54:21 UTC 2012
2.Ubuntu 12.04x64:
Linux version 3.2.0-49-generic (buildd@komainu) (gcc version 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #75-Ubuntu SMP Tue Jun 18 17:39:32 UTC 2013
Help me, please, send me your debug logs as I wrote above. Or write more details and I will try to reproduce it again. If you have too much trouble about this problem, you may ask our support team, they will help you.