Normal backup matching most files in source though none were changed

[jsunderwood]

Retrospect (Windows) 7.5.387

Three desktop computers, connected by wired ethernet (Draytek 2600 router and an ethernet switch.

All three running Windows XP Pro SP2.

Buffalo Terastation Network Attached Storage (NAS) running RAID 5 on four x 250GB drives.

Quantum Travan 20/40 GB USB tape drive.

 

One computer acts as server. Normally its only action is to run our multi-user mail client but the data is held on the NAS device. It also runs Retrospect to back up itself and the other two machines as Retrospect clients.

 

Important data from the workstations is mirrored on the NAS device (using Techsoft Mirrorfolder).

 

Backups are as follws:

Daily, the server machine is backed up completely (except temp files) and also all current data on the NAS, including the mirrored data from workstations (this is to avoid having the workstations turned on at that time as well as providing continuous backup between the Retrospect ones).

 

On a weekly basis, less volatile data is backed up to different backup sets.

 

The systems on the two workstations (each to its own backup set)

 

Archive data held on the NAS. This is old data which will eventually be copied to CD or DVD for long term storage. The more recent will be kept immediately available as long as it can be backed up.

 

These three weekly backups always work perfectly. In particular, Retrospect correctly identifies the files held on the NAS that have been changed or not.

 

The problem arises with the largest backup, long term storage which includes most of our pictures (those taken within the last 1-2 years are in the daily backup); a number of recorded video and sound rm files and copies of program installers currently in use with some older versions.

 

A recycle backup or normal backup to deleted tapes works correctly. Currently 19.9GB is copied to the tape which is the size of data reported by the Operating System. Yesterday I ran such a backup and this morning, with no files in the relevant folder changed, deleted or added, ran a normal backup. This time, the scan initially reported 19.9GB and then proceeded to start backing up 19.1GB.

 

I have tried forgetting the backup set and even deleting the script and starting again. I did wonder if it is a problem with time synchronisation between the NAS and the backup machine, but if that were the problem, it would apply to the other, successful, backups which carry out the same task of matching files on the NAS.

 

One aspect puzzles me. Why, if it is not going to match the unchanged files correctly, does it not want to back up the entire volume?

 

My next step is to reduce the size of the long term backup (the problem one) by moving stuff to archive. (That is something which needs doing anyway). One possibility may be that the problem is caused by the first backup crossing into a new tape. However, this would only work round a problem which still remains.

[jsunderwood]

Reducing the size of the data to less than a single tape appears to have solved the problem, for the moment. I still can't see why it should not be possible to back up correctly even if the data overflows onto a second tape. Verification is against MD5 so there is no need to read the tapes twice.

[volpine22]

I now (again) have the same problem with a 350gb D2D backup. I previously solved it by turning off (under options) Backup file security. However, after recently initiating a new backup of the data, the problem still happens even with Backup file security turned off. I am running multiserver 7.5.285, hotfix 7.5.12.103. Does anyone else have similar experiences, possible solutions?

 

Thanks!

Jim