corrupt compressed backuped files

[krapaud]

Hi!

I use arcserve 7 to backup data on a storagetek L20 library (DLT 40/80).
I first used the 'enable compression' option whenever i submitted a job. I found out when i restored some office documents (.doc, .xls & .ppt) that many of them where corrupted. I disabled the compression and now i can restore my files without them being corrupted.
But the problem does not occur on all files : on the same tape with the compression enabled i have two excel documents. I restored both of them, one was corrupt, the other not. All word and powerpoint documents are corrupt.
Since i disabled the compression the problem disappeared. But i still need to restore some older files and for example, a 100ko word document will be restored as a 3ko empty document.

do you know a way i could restore my compressed files?

thanks

 

[Cyklops]

there are some fixes that refer to corrupted files when restoring form backups that used (software) compression.
Check them on

http://support.ca.com/Download/patches/asitnt/arc_eng_menu.html

Be sure to have at least Sp4 applied (build 1100)

regards

 

[krapaud]

In fact Arcserve is up to date, I applied all patches and SP available.

I found out something new as I did some tests :
I created a word document using MS Office, and another Word document using openoffice. I wanted to check whether the compression bug was dued tu MS headers or to see if it is only a bug in Arcserve.
I scheduled a backup on tape, the same tape I usually use and activated software compression.
I had a waring in the event log saying that software compression was disabled due to hardware compression.
I never had had that message before and my word documents were restored without missing content or whatever.
So it really is an Arcserve bug, or a failure in my SCSI/Library device.

If you have any ideas...

Thanks

 

[Cyklops]

This is how ARCserve should work : If hardware compression is enabled (and most of the time it is unless you disable this on BIOS or jumper settings level) ARCserve will automatically disable software compression.
Did you do any other configuration changes prior to this jobtesting ??

regards

 

[krapaud]

No, I have not changed anything and that's what bothers me so much. I can't find out what makes the switch between software and hardware compression so unstable.
It is month since I defined my rotation shemes but nothing helps it.

I guess there has been both a software compression and then an hardware compression and that's why I can't get my data back. CRC's must have been badly corrupted so I don't think I'll be able to get anything back :/

 

[davidmichel]

There is another possiblity. ARCserve will maintain the compression status of a tape. So if a tape was formated with hardware compression disabled, it will maintain that status. For such a tape hardware compression would be disabled for that job and the backup would use the software compression.

 

[krapaud]

Well I didn't know hardware compression could be bypassed. The library is a storagetek L20 and I've never been able to found any menu to change compression settings.
If hardware compression can be switched off for a tape then I guess it must be through Arcserve itself and I never use the format menu but only the quick erase plus menu. And my tapes are all of the same brand and were all replaced at the same time so I can't understand why hardware compression would be disabled on some of them and not on all. Moreover some files (.xls) on the same tape, the same session and even the same directory can be restored without being corrupted but others will appear being truncated.
Anyway could you explain me how hardware compression can be disabled, I may want to try that, could help me on some files.
Thank you.