Wh1mpy Posted July 4, 2009 Report Share Posted July 4, 2009 We are running Retrospect Multi Server Version 7.6.123 Driver update and Hot Fix, version 7.6.2.101 on Windows Vista Business SP1-32 bit with all the latest fixes and 4Gb RAM. Intel Core2Duo E6850. Lately I get several "didn't compare" errors on the nightly backup. What does this mean and how do I fix it? I searched the FAQ and this forum. But no answer. Quote Link to comment Share on other sites More sharing options...
Ramon88 Posted July 7, 2009 Report Share Posted July 7, 2009 Either (some of) your files have changed between them being copied and verified or your storage medium might have a problem. This considering your system runs stable. What is your backup target? A tape drive, optical, hard drive? Can you test using a different storage device? Are users logged out from their machines when they are being backed up and verified? Quote Link to comment Share on other sites More sharing options...
Wh1mpy Posted July 8, 2009 Author Report Share Posted July 8, 2009 My (only) backup target is a tape drive. (I don't have a spare one.) I am very sure that there are no users logged in when the backup script is running. Yesterday I had 119 didn't compare errors, so during the day I tried a rebuild of the Catalog file. I seemed it helped a bit because now I had (just) 11 didn't compare errors. I also read somewhere that I could also try to move the data to a different disk and then move the data back. This would force the computer to write the data again to the disk. I didn't try this, but do you think it could help? (sorry for my bad English, in het Nederlands gaat het een stuk makkelijker) Quote Link to comment Share on other sites More sharing options...
Ramon88 Posted July 8, 2009 Report Share Posted July 8, 2009 *L* A fellow Dutchman? Well, why would you do a catalog rebuild? It only makes a catalog (it's just an index) from the tape. It's not the way you would be able to test for compare errors. If you have compare errors the most likely cause would be a problem with the tape or the drive. For troubleshooting you can try to attach an external or internal harddrive. Or maybe your machine running Retrospect has enough spare storage? Create a Disk Catalog on the newly attached drive. Name it "Test" or something. After that make a duplicate of your backup script and the destination entry for that script into your newly created Disk Catalog. Run it as a test in the off hours and see if you get the same compare errors. If you don't, you can be certain it has something to do with your tape drive or tape. Remember tapes and tape drives wear down with usage. Tapes can only be uses an x-amount of times. We used to have AIT and DAT drives and sometimes compare errors were resolved with a cleaning tape and sometimes it was a termination problem (SCSI). Nowadays we use harddrives and diskpacks. It's faster and so far has proven more reliable. I just don't like tape anymore I guess. Too much hassle and slow compared to even a simple SATA drive. Quote Link to comment Share on other sites More sharing options...
rhwalker Posted July 8, 2009 Report Share Posted July 8, 2009 Lately I get several "didn't compare" errors on the nightly backup.What does this mean ... ? This was answered correctly above: (some of) your files have changed between them being copied and verified and how do I fix it? Either: (1) Don't back up files while they are changing. Some of the changing files may be log files, etc., that are normally and always changing. You might choose to ignore these errors. or (2) Use the MD5 checksum to validate your files, such that the saved data in the backup set is verified against the MD5 checksum of the file at the time it was written, rather than comparing against the file at verification time (which might have changed). I am very sure that there are no users logged in when the backup script is running. Doesn't matter. The computer was still running. Things were still changing. Yesterday I had 119 didn't compare errors, so during the day I tried a rebuild of the Catalog file. I seemed it helped a bit because now I had (just) 11 didn't compare errors.I also read somewhere that I could also try to move the data to a different disk and then move the data back. This would force the computer to write the data again to the disk. I didn't try this, but do you think it could help? These are red herrings and have nothing to do with the problem or the solution. Russ Quote Link to comment Share on other sites More sharing options...
Ramon88 Posted July 8, 2009 Report Share Posted July 8, 2009 To add to this, MD5 checksum validation would also show a nice performance gain. Especially when backing up to tape. To avoid some compare errors Retrospect has a nice exclude function. See under "Configure > Selectors". Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.