Simultanenous executions of ontape to disk?
Question (IDS 9.4): what happens if a cron-driven 'ontape -a' logical log backup to disk is still running when the next one starts 15 minutes later, possibly alongside a level-0 archive to another disk file? Answer from Art Kagel: the second ontape simply errors out and exits, so nothing worse than a failed backup — it won't crash or freeze the engine. He noted an old race condition where the second ontape could hang if it checked shared memory just as the first was cleaning up, but believed that was fixed long ago.
Auto-generated by DrWatson from the posts below — may be imperfect; read the full thread.
Hi everyone. With IDS 9.4.....If we had a cron that executes say Ontape
Logical log backups (ontape -a) every 15 mins or so, and LTAPEDEV is written
to a disk file.....and by chance ONTAPE process_1 has not completed within 15
minutes and the cron kicks off ONTAPE process_2.....would you expect this to
be a problem? Or is IDS 9.4 smart enough to handle this properly by
serializing it safely? Also, in addition to having 2 ONTAPES running backing
up logical logs to DISK....we also kicked off a Level0 to disk (albeit a
different DISK location)? So the hypothetical picture here would be:
ontape -a (#1) writing to DISK_FILE_1 starts
ontape -a (#2) writing to DISK_FILE_1 starts (and ontape -a (#1) is stillrunning
ontape -s -L 0 kicks off writing to DISK_FILE_2Now they are all running at the same time....
what would you expect to happen?
Thanks
the second instance will get an error and exit if the first one is still
running.
Art
On Thu, Oct 9, 2008 at 8:27 PM, WILL LANDSTROM <willlandstrom@yahoo.com>wrote:
> Hi everyone. With IDS 9.4.....If we had a cron that executes say Ontape
> Logical log backups (ontape -a) every 15 mins or so, and LTAPEDEV is
> written
> to a disk file.....and by chance ONTAPE process_1 has not completed within
> 15
> minutes and the cron kicks off ONTAPE process_2.....would you expect this
> to
> be a problem? Or is IDS 9.4 smart enough to handle this properly by
> serializing it safely? Also, in addition to having 2 ONTAPES running
> backing
> up logical logs to DISK....we also kicked off a Level0 to disk (albeit a
> different DISK location)? So the hypothetical picture here would be:
>
> ontape -a (#1) writing to DISK_FILE_1 starts
> ontape -a (#2) writing to DISK_FILE_1 starts (and ontape -a (#1) is still> running
> ontape -s -L 0 kicks off writing to DISK_FILE_2> Now they are all running at the same time....
>
> what would you expect to happen?
>
> Thanks
>
>
>
>
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> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
--
Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (art@iiug.org)
Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Oninit, the IIUG, nor any other organization
with which I am associated either explicitly or implicitly. Neither do
those opinions reflect those of other individuals affiliated with any entity
with which I am affiliated nor those of the entities themselves.
Hi Art. Thanks. This would not really be a problem though, correct? Other than
the second ontape failing that should be the extent of the problem..would you
agree? In other words this scenario should not crash Informix or cause
Informix to freeze? Would you agree?
Hi Art. Thanks. This would not really be a problem though, correct? Other than
the second ontape failing that should be the extent of the problem..would you
agree? In other words this scenario should not crash Informix or cause
Informix to freeze? Would you agree?
Hi Art. Thanks. This would not really be a problem though, correct? Other than
the second ontape failing that should be the extent of the problem..would you
agree? In other words this scenario should not crash Informix or cause
Informix to freeze? Would you agree?
No, no huge problems. Worst case I've seen is there used to be a small race
condition under which the second ontape would end up hung if it checked
shared memory just as the first on was exiting and cleaning up. Think that
was fixed a while ago.
Used to run into this using the ALARMPROGRAM to back up logs when logs were
filling fast enough and the original version of my eventalarm.c didn't
ignore the new message while the ontape was still running.
Art
On Thu, Oct 9, 2008 at 10:59 PM, WILL LANDSTROM <willlandstrom@yahoo.com>wrote:
> Hi Art. Thanks. This would not really be a problem though, correct? Other
> than
> the second ontape failing that should be the extent of the problem..would
> you
> agree? In other words this scenario should not crash Informix or cause
> Informix to freeze? Would you agree?
>
>
>
>
*******************************************************************************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
--
Art S. Kagel
Oninit (www.oninit.com)
IIUG Board of Directors (art@iiug.org)
Disclaimer: Please keep in mind that my own opinions are my own opinions and
do not reflect on my employer, Oninit, the IIUG, nor any other organization
with which I am associated either explicitly or implicitly. Neither do
those opinions reflect those of other individuals affiliated with any entity
with which I am affiliated nor those of the entities themselves.