Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller

IDK about multiple media classes, but there are some options within a media class which do intrigue me.  For example, we never use *PERM on tapes.  We always set a retention period in the control group.  When the tape expires it just gets reused automatically and rewrites over the data on the tape.  There's an option in the media class to initialize the tape when it expires.  Normally a "who cares" kind of thing but if you really want to make sure data is gone on an *EXP tape there's your option there.  This actually was a thing here.

But in general, I agree with you and we tend to only differentiate media classes for different media types.  You know, ULTRIUM5 vs ULTRIUM7 kind of things.

Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller

Thanks Rob for your valued input!

I'm glad you mentioned the "initialize on expire" option.  It actually seems to be an important option to turn on with a VTL solution.  There's no "cost" in having the system "load" a virtual tape and initialize it, like there would be with a physical tape.  I've worked with two different VTL solution providers and both told me to make sure that setting is turned on within the media classes that we're using.

I'm curious to see if anyone has any specific use cases for multiple media classes, aside from actual different media types.  I've come across an environment where 10 LPARs are all using a single media class for all backups, but in one oddball LPAR they're using 8 different media classes but nobody seems to know why.  "It's always been that way." :D

------------------------------
Steven Riedmueller
Certified IBM i Admin
Speaker, Mentor, and Advocate

Original Message:
Sent: Thu May 29, 2025 02:36 PM
From: Robert Berendt
Subject: BRMS media class uses

IDK about multiple media classes, but there are some options within a media class which do intrigue me.  For example, we never use *PERM on tapes.  We always set a retention period in the control group.  When the tape expires it just gets reused automatically and rewrites over the data on the tape.  There's an option in the media class to initialize the tape when it expires.  Normally a "who cares" kind of thing but if you really want to make sure data is gone on an *EXP tape there's your option there.  This actually was a thing here.

But in general, I agree with you and we tend to only differentiate media classes for different media types.  You know, ULTRIUM5 vs ULTRIUM7 kind of things.

------------------------------
Robert Berendt IBMChampion
Business Systems Analyst, Lead
Dekko
Fort Wayne

Original Message:
Sent: Thu May 29, 2025 12:48 PM
From: Steven Riedmueller
Subject: BRMS media class uses

Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller

------------------------------
Steven Riedmueller
Certified IBM i Admin
Speaker, Mentor, and Advocate
------------------------------

Thanks Rob for your valued input!

I'm glad you mentioned the "initialize on expire" option.  It actually seems to be an important option to turn on with a VTL solution.  There's no "cost" in having the system "load" a virtual tape and initialize it, like there would be with a physical tape.  I've worked with two different VTL solution providers and both told me to make sure that setting is turned on within the media classes that we're using.

I'm curious to see if anyone has any specific use cases for multiple media classes, aside from actual different media types.  I've come across an environment where 10 LPARs are all using a single media class for all backups, but in one oddball LPAR they're using 8 different media classes but nobody seems to know why.  "It's always been that way." :D

IDK about multiple media classes, but there are some options within a media class which do intrigue me.  For example, we never use *PERM on tapes.  We always set a retention period in the control group.  When the tape expires it just gets reused automatically and rewrites over the data on the tape.  There's an option in the media class to initialize the tape when it expires.  Normally a "who cares" kind of thing but if you really want to make sure data is gone on an *EXP tape there's your option there.  This actually was a thing here.

But in general, I agree with you and we tend to only differentiate media classes for different media types.  You know, ULTRIUM5 vs ULTRIUM7 kind of things.

Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller

Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller

Hi all,

A good reason to define at least two classes for the same format (like ULTRIUM5 or 7, for example) is when you have a VTL-type library.

A parameter inside the media class allows you to define a media reset upon expiration. This reset is handled by the maintenance job (STRMNTBRM).

This frees up the disk space used by the volume within the disk array attached to the VTL. If you don't do this, the disk space allocated to tape is not "cleaned up".

This option has been available since V5R4 (in a different form at the time) with the use of virtual tapes defined within IBM i.

I'm familiar with the subject because I was the source of this incident.

At the time, the IBM i Service Point developed programs to overcome this deficiency while waiting to have the appropriate PTFs.

This fix allows the deletion of virtual data to be applied, whether internal to the IBM i or in a VTL.

In France, I have many clients who have a VTL, but some still want to outsource their tapes. Furthermore, some want to outsource encrypted tapes.
To avoid using physical tape, it makes sense to have a second, remotely replicated VTL, but the infrastructure costs are sometimes prohibitive for some clients.
In summary, many clients have two types of libraries: physical and VTL, but not one or the other.
When they have a VTL, they keep their physical library for duplication or to perform SAVSYS or SAV21 from time to time.

Hi all,

A good reason to define at least two classes for the same format (like ULTRIUM5 or 7, for example) is when you have a VTL-type library.

A parameter inside the media class allows you to define a media reset upon expiration. This reset is handled by the maintenance job (STRMNTBRM).

This frees up the disk space used by the volume within the disk array attached to the VTL. If you don't do this, the disk space allocated to tape is not "cleaned up".

This option has been available since V5R4 (in a different form at the time) with the use of virtual tapes defined within IBM i.

I'm familiar with the subject because I was the source of this incident.

At the time, the IBM i Service Point developed programs to overcome this deficiency while waiting to have the appropriate PTFs.

This fix allows the deletion of virtual data to be applied, whether internal to the IBM i or in a VTL.

Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller

We have used media classes for a software-based VTL environment where we only want to replicate certain virtual tapes to another remote VTL e.g only weekly/monthly backups. To do this within the VTL software the tapes are part of 2 distinct pools, one pool with tapes set to be replicated and the other pool for non-replicated tapes. The only way we can force BRMS to 'pick' from the the correct pool of tapes e.g tapes to be replicated , is by adding tapes with a media class named REPLICATE or NONREPLICATE. These are then picked from the correct VTL pool (the backup media policy points to the correct class for the backup) and replicated/not replicated as required.

Granted this might just be a configuration quirk of the VTL software we use.

Thanks

Mark Waterhouse

Technical Consultant

Hey all,

There's a great conversation going on about the BR1>BR2 migration, and about BRMS as a whole.  This lead me to ask a question about the concept of "media class" in BRMS. 

If all of your tapes are the same density (i.e. ULTRIUM5), what is the benefit of using multiple media classes?  From my perspective (using a VTL) there isn't much to be gained by using different media classes.  It actually creates a situation where a backup might complain about not having available media of X class, when in reality there is plenty of available tape media in the library.

The control group sets the retention along with many other attributes of the backup.  So when does using different media classes become useful?

Thanks,
Steve Riedmueller