[Info-vax] Backup verify problems

[Jan-Erik Söderholm]

Richard B. Gilbert wrote:
> DJ wrote:
>> On Jan 30, 3:26 pm, gsdguy <peter... at chem.washington.edu> wrote:
>>> I am getting backup verify errors and I don’t know why. I hope someone
>>> can explain what is happening.
>>>
>>> I had a disk and tape drive failure and restore the disk from a backup
>>> tape ( I bought a new DAT tape drive). I decided to start using the /
>>> verify switch when I do backups. When I did my first backup to tape
>>> with /verify I got verify errors like the ones shown below.
>>>
>>> %BACKUP-E-VERIFYERR, verification error for block 31 of DUA2:[LEROY]
>>> MAIL.MAI;1
>>> %BACKUP-E-VERIFYERR, verification error for block 32 of DUA2:[LEROY]
>>> MAIL.MAI;1
>>> %BACKUP-E-VERIFYERR, verification error for block 33 of DUA2:[LEROY]
>>> MAIL.MAI;1
>>> %BACKUP-E-VERIFYERR, verification error for block 34 of DUA2:[LEROY]
>>> MAIL.MAI;1
>>> %BACKUP-E-VERIFYERR, verification error for block 35 of DUA2:[LEROY]
>>> MAIL.MAI;1
>>> %BACKUP-E-VERIFYERR, verification error for block 36 of DUA2:[LEROY]
>>> MAIL.MAI;1
>>>
>>> I created a disk backup saveset and got the same verify errors. I
>>> checked the error log for any hardware errors and there were no
>>> errors. I then restored one of the files that had verify errors to
>>> another disk and did a difference between the original file and the
>>> restored file. The difference program said that there was no
>>> difference between the two files. I also did an analyze/disk on the
>>> disk drive and there are not errors.
>>>
>>> Can someone explain what is going on? How can I get rid of these
>>> verify errors? Thank you.
>>
>> Dear GSDGUY:
>>
>> Backing and verifying on any volatile file will cause this problem. At
>> time = 0, you backup the email file, then at time = 2 hours you are
>> verifying what you back up onto tape. However, during this time
>> “Leroy” has deleted some email messages, thus causing the backup
>> verification error to occur. The information store in the mail.mai
>> file has been deleted.
>>
>> Regards,
>> Daryl Jones
> 
> If you can't, somehow, quiesce the system, or at least the disk, while 
> you make your backup, you may not be able to restore everything in 
> usable form!
> 
> Databases, e.g. Oracle, can sometimes make a "snapshot" of a filesystem 
> that allows you to get a consistent backup.  Lacking such a feature, 
> your choices are to take the disk offline or to live with the 
> possibility that something will be lost if you have to do a restore.

If using Oracle *Rdb*, this is of course a non-issue. Online
backup is designed into the product. It's as simple as specifying
/ONLINE inthe RMU /BACKUP command.