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==== Tape restore Adv. Rev. and server compression (AREV Specific) ====
=== At 15 JUN 1998 05:58:38PM Ron Griffith wrote: ===
{{tag>"AREV Specific"}}
Has anyone out there had a problem restoring Advanced Revelation systems from Tape Backup (we use the Cheyenne tape backup system) when there is server compression enabled? We are getting corrupt data returned from the restore job (i.e. a Group Format Error appears when we do the GFE check). If this has happened to you, did you disable the server compression? Did that solve the problem. We are running a system named DMS written by Multidata in California on a Netware 4.1 network operating system. Any help would be appreciated.
Thanks - Ron G
Tha
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=== At 15 JUN 1998 06:57PM Jeff Blinn wrote: ===
I haven't had a problem with backup compression in general - I do seem to remember some backups have a switch for zero byte files. If files are restored without both parts (*.lk & *.ov) you could have some problems. It's fairly common for smaller files to have a zero byte *.ov file.
Other than that, the files 'should' restore to their original state no matter what type of compression is being used to back them up. Do you get any errors during the backup/restore process? Were the files verified after they were backed up? Is it possible the errors existed when the backup was made? Of course - these aren't the kinds of questions you want to deal with when you need to restore from a backup . . .
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=== At 15 JUN 1998 07:01PM Ooops wrote: ===
I read your original post wrong - you're talking about 'server' compression, not backup/tape compression. Sorry about that.
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=== At 16 JUN 1998 11:02AM Victor Engel wrote: ===
Don't forget that unless you ensure that an Arev file is not being modified during the backup process, even with a successful backup, where no files were open during backup, you could have a GFE in your restored file. Condider the following scenario:
You have a system with 200 Arev files, with corresponding DOS filenames named REV20001.LK through REV20201.LK and REV20001.OV through REV20201.OV. Now, let's suppose that the backup process sorts by extention, so all the *.LK files are backed up before the *.OV files. The first file to be backed up in REV20001.LK in this scenario, and 200 files are processed before REV20001.OV is processed. Suppose it takes an hour to process these 200 files and in the mean time, someone logged on an modified the Arev file corresponding to REV20001.LK and REV20001.OV. Not only that, the modification resulted in the file being resized, and the user logged out before the hour was finished. Now the backup finally gets to REV20001.OV, the file is not open, so the backup continues merrily on its way. However, REV20001.LK and REV20001.OV are not in sync, and when a restore is performed, the file has a GFE.
I'm not saying this happened in your case. I'm just saying it's something to keep in mind when setting up backup procedures.
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