Omniback tape slot selection with DLT library

Omniback tape slot selection with DLT library

Post by andy_penning.. » Sat, 06 Jan 2001 20:09:23



We are using Omniback II 2.55 with a DLT library.
When a (particular) backup is initiated, the job selects a tape from
the pool (say ABC123), and the library is requested to select the tape
from slot 25. This turns out to be an empty slot (the tape is actually
in slot 44). Omniback II does know that this tape is in slot 44 because
if I go scan slot 44, it reads the tape. Indeed if I look at the media
pool, it tells me ABC123 is in slot 44.

Can someone tell me why the backup is attempting to load from slot 25
when the tape is in 44?

And what is the way to force the backup to go ask the database for the
correct slot number?

Rescan the library?

Thanks in advance, Andy.

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Omniback tape slot selection with DLT library

Post by Timothy J. Regan I » Sun, 07 Jan 2001 00:57:15


Andy,

You need to rescan the library to sync the database with the DLT exchanger.
If your Exchanger has barcode support then performa barcode scan.

Best Regards,

Tim Regan


>We are using Omniback II 2.55 with a DLT library.
>When a (particular) backup is initiated, the job selects a tape from
>the pool (say ABC123), and the library is requested to select the tape
>from slot 25. This turns out to be an empty slot (the tape is actually
>in slot 44). Omniback II does know that this tape is in slot 44 because
>if I go scan slot 44, it reads the tape. Indeed if I look at the media
>pool, it tells me ABC123 is in slot 44.

>Can someone tell me why the backup is attempting to load from slot 25
>when the tape is in 44?

>And what is the way to force the backup to go ask the database for the
>correct slot number?

>Rescan the library?

>Thanks in advance, Andy.

>Sent via Deja.com
>http://www.deja.com/


 
 
 

Omniback tape slot selection with DLT library

Post by Jack Perd » Fri, 19 Jan 2001 02:58:08


My experience is that OBII 2.55 is a bit brain dead
when it comes to Mount Request for media from a
pool that no more media available from, either because
they: a) are all full, b) have been degraded to "fair"
condition, or c) are uninitialized).

e.g. I have pool XYZ that uses slots 6-11... however,
     when the media get full, the mount request (and
     error on the backup) complain about their not
     being media for pool XYZ in slot 1 (or 2, but not 6-11)
     [I have barcodes and have tried rescanning, but
     neither seems to help this situation].

Making sure you have space available in the pool
might help. (???)

HIH,

jack


>We are using Omniback II 2.55 with a DLT library.
>When a (particular) backup is initiated, the job selects a tape from
>the pool (say ABC123), and the library is requested to select the tape
>from slot 25. This turns out to be an empty slot (the tape is actually
>in slot 44). Omniback II does know that this tape is in slot 44 because
>if I go scan slot 44, it reads the tape. Indeed if I look at the media
>pool, it tells me ABC123 is in slot 44.

>Can someone tell me why the backup is attempting to load from slot 25
>when the tape is in 44?

>And what is the way to force the backup to go ask the database for the
>correct slot number?

>Rescan the library?

>Thanks in advance, Andy.

>Sent via Deja.com
>http://www.deja.com/

 
 
 

Omniback tape slot selection with DLT library

Post by Luka Renk » Sat, 20 Jan 2001 00:33:11




> We are using Omniback II 2.55 with a DLT library.
> When a (particular) backup is initiated, the job selects a tape from
> the pool (say ABC123), and the library is requested to select the tape
> from slot 25. This turns out to be an empty slot (the tape is actually
> in slot 44). Omniback II does know that this tape is in slot 44
because
> if I go scan slot 44, it reads the tape. Indeed if I look at the media
> pool, it tells me ABC123 is in slot 44.

> Can someone tell me why the backup is attempting to load from slot 25
> when the tape is in 44?

OmniBack selects medium for backup according to allocation policy.
First of all you have to know what allocation policy is selected for
your media pool. If the policy is Strict, OmniBack will only use valid
OmniBack media from that pool and will not try to iniaitlize new media.
However, if you have Loose policy, depending on "Allocate unformatted
media first" option, OmniBack will also try to initialize new media.
Candidates for initialization are all library slots marked as Blank or
Unknown.

BTW, you can always view the order in which OmniBack will try to
allocate media with the following commands:
   # allocation from pool
   omnimm -show_pool_alloc <Pool>

   # allocation from pool fro particular library
   omnimm -show_repository_alloc <Library> <Pool>

If I try to explain what happened in your case:

1. your ABC123 pool has Loose policy with "Allocate unformatted media
first" option enabled,

2. Slot 25 was marked as Blank/Unknown in OmniBack database (OmniBack
was not aware that the slot was not empty) or

3. OmniBack was not aware that you have valid medium from ABC123 pool
in slot 44,

4. OmniBack probably selected slot 25 because it wanted to initialize
new media

How to overcome such behaviour: change pool policy to Loose
with "Allocate unformatted media first" set to Off or use Strict pool
policy. Also, ensure that OmniBack database is up-to-date with actual
repository of the library (perform rescan of library or enter/eject
media to/from library only with OmniBack commands).

Quote:

> And what is the way to force the backup to go ask the database for the
> correct slot number?

If you want to force OmniBack to use particular media (which can
implicitly mean the slot too), you should look for OmniBack
Preallocation list (specified list of media that should be used for
backup).

Quote:

> Rescan the library?

> Thanks in advance, Andy.

Regards,
Luka

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Omniback tape slot selection with DLT library

Post by Luka Renk » Sat, 20 Jan 2001 00:51:52




Quote:

> My experience is that OBII 2.55 is a bit brain dead
> when it comes to Mount Request for media from a
> pool that no more media available from, either because
> they: a) are all full, b) have been degraded to "fair"
> condition, or c) are uninitialized).

> e.g. I have pool XYZ that uses slots 6-11... however,
>      when the media get full, the mount request (and
>      error on the backup) complain about their not
>      being media for pool XYZ in slot 1 (or 2, but not 6-11)
>      [I have barcodes and have tried rescanning, but
>      neither seems to help this situation].

> Making sure you have space available in the pool
> might help. (???)

Pools are logical grouping of media - not physical grouping of media.
When there is not enough media available in the library, OmniBack will
issue a mount request for new media to be entered in library. OmniBack
will ask the user to put the media in particular slot - this slot is
selected according to some rules. AFAIK, the order seems to be:
1. Empty slot (if any)
2. Slot with non-OmniBack (tar/cpio/...) media (if any)
3. Slot with OmniBack Foreign (not in DB) media (if any)
4. Slot with OmniBack media from other pools
5. Some other slot...

However, you as the user have an option to ignore the slot OmniBack
actually suggested. You can remove your Full/Poor/Fair media and enter
new media on their slots (in your case 6-11). You just have to ensure
that OmniBack is aware of the change (perform enter/eject of media with
OmniBack or rescan slots/barcodes). Then you can confirm the mount
request. OmniBack will first try the slot it was proposed and found out
that the requested medium is not there, it will return medium back and
next allocation process will select new medium from slots 6-11 (where
you have entered new media)...

> HIH,

> jack


Regards,
Luka

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Omniback tape slot selection with DLT library

Post by Frank Slootwe » Sat, 20 Jan 2001 23:20:53


[deleted]

Quote:> Rescan the library?

  Yes, rescanning the library is the most likely fix. As others have
posted, there can be other reasons for OmniBack, seemingly, trying, to
pick the 'wrong' tape/slot, but the OmniBack *software* list
(repository) being out-of-sync with the actual *hardware* status, is the
most likely cause and is cured by a (OmniBack) rescan of the library. To
prevent problems like this, *always* use OmniBack to manipulate tapes
(i.e. load, unload, move, eject) and *never* anything else (i.e. not the
hardware controls, not uma(1M), not mc(1M), etc.). People often wonder
why this is and think it is a bug. The point is that the hardware only
knows if there is *a* tape in a slot. OmniBack also needs to know
*which* tape is in a particular slot. The only way to know that for sure
is by reading (scanning) the (software) label from the tape. Because
scanning a big library can take a lot of time and should not be needed,
OmniBack does not do that by default.
 
 
 

1. DLT-Library with Omniback problem (unmounting drive)

Hi

A couple of months ago i asced the same Question and someone helped me
in this newsgroup. Unfortunately i didn't make a big note of this command
like i should. So this ist the Problem.

We have a DLT-Library with 2 drives. Drive 1 is blocked by a Tape and this
Tape won't come out. So the other Backups are blocked because of this
tape. I know, there was s simple command to force the tape into it's slot.

Thanks for any help.

Bye
--
Marcus Siegl
Tel.  : 07071-9457-408, Fax : 07071-9457-110
Post  : science + computing GmbH , Hagelocher Weg 71 , 72070 Tuebingen

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