Logical log backups 
Author Message
 Logical log backups

Dear netters,

We have necountered what appears to be a problem with backing
up logical logs to tape.  Some logs are not being backed up.

We are running on-line 5.0 on a IBM6000 model 580. We backup
logs to 8mm tape.

Generally,  it appears that under certain circumstances
tbmonitor's continuous backup fails to correctly record what it
backed up to tape. More specifically, it reports to the screen and to
the online log file completion of backups that did
not occur.

The most recent example.
Our dedicated terminal running continuous backup reported
"Error writing to tape device Error #5
Please label as #1 in the log tape sequence" and then
it displayed log numbers  10485-10573.
The online log file reported both the completions and
backups of all of these logs.

Examination of the backup tape shows that the last log on
the tape in question is log 10571. tblog also reports a
Error No.= 110 at the end of the log.  I assume it encounters
an end of volume there as the tblog run is not selecting out
any log number. Log 10571 appears to be
a complete logical log.  The next tape used by continuous backup
shows that the process picked up at log 10574.

The contents of the log as displayed by tblog show that
the final transaction logged on 10571 was committed about
25 minutes before the first transaction was begun on 10574.
The onlind log file recorded the completions and backups of
log 10572 and log 10573 at reasonable intervals within that
25 minute period.

At that time of a business day no transactions in that period is
not possible.

We have had two other instances of missing a single log at
the end of a tape volume, one of which is muddied up by some
other operational problems, but the other appears to be a lost
logical log.

Part of the complication of describing this is some concern
that tblog might not behave as it should.  It might help find the
problem if any of you have had and can describe similar
instances in your experience.  Even better would be your
identification of something we are doing wrong.

We try not to cry wolf, and we are concerned

Con Woodall                     * "You can do anything
Colorado State University       * with a computer, but
Veterinary Teaching Hospital    * you might not want to."
Fort Collins, CO  80523         * --Larry Whatshisname
303-491-1244,  FAX 303-491-4414 * or Lauri Whatshername


Mon, 22 Apr 1996 02:33:05 GMT
 [ 1 post ] 

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