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Two tape cartridges in one media set - which one will be chosen?

Created: 11 Dec 2013 • Updated: 28 Jan 2014 | 8 comments
This issue has been solved. See solution.

Hi,

Let's say I have a media set containing one tape which is used and written daily. Let's say the allocated date is 02-Dec-2013

I now add another new tape cartridge to the same media set and erase it so the allocated date is 11-Dec-2013.

On the next backup, which tape will be used? The new one of the older one?

 

Operating Systems:

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pkh's picture

The one with the oldest allocated date will be used first

YonatanC's picture

Thanks pkh,

I wanted to confirm here because when I was on the line with Tech Support they told me the opposite and it didn't sound right to me...

So if I have a half-full media and I add a new blank media, BE will first finish writing on the half-full one and only than will it take the new one, correct (assuming it's set to never overwrite, allways append)?

pkh's picture

If your job specify append otherwise overwrite and there is an appendable (half-filled) tape, it will write to the that tape first before overwriting a second tape.  However, if the half-filled tape is not appendable, then it will switch to overwrite mode and then it would choose overwritable tapes based on which has the oldest allocated date.  The oldest allocated date comes into play when there is more than one suitable tape.

In your scenario, the new tape would not be used because it is protected forever.  BE needs an ovewritable tape for the 2nd and subsequent tape.  It cannot append to a second tape.  It can only append to the first tape.

YonatanC's picture

Something doesn't adds up...

My scenario is this:

Media set properties: OPU=Infinite - "Don't Allow Overwrite" AU="Infinite - Allow Append"

Under Tools>Options:

Media Overwrite Protection Level = Partial - protect only allocated media

Media overwrite options = Overwrite scratch media before overwriting recyclable media contained in the targeted media set

The job definitions = Appent to media, terminate job if no appendable media is available

 

So to my understanding,

BE will first use the half-full tape because its allocated date is older. When the half-full tape would be full it will not be appendable anymore, so BE will look for another appendable media (according to the job definitions). It will than find the new blank media in the media set, which is not overwritable but is appendable.

Am I missing something?

 

pkh's picture

As I said before, BE cannot append to a second tape.  After appending to the first tape, for the 2nd and subsequent, it must have an overwritable tape.  Since you put the new blank media in the media set, it is immediately write-protected forever and thus cannot be overwritten, even though it is empty.  To use the new tape, you got to put it in the scratch media set.

You only use infinite write protection for very special tapes.  For other tapes, you should set a reasonable OPP.  Otherwise, you would run out of tapes very soon.

SOLUTION
YonatanC's picture

OK, I understand.

So how come when I take the full tape out every couple of weeks, and put a single new blank tape in that media set (so there's only one tape in that media set) it manages to use it? I never put it in the scratch media set.

Is it because it's not a continuem of the previous tape?

Colin Weaver's picture

A few things to understand

Media is moved automatically between media sets as and when Backup Exec requries to move them - there is a table in the admin guide that explains the various settings that affect how overwriteable media is chosen.

Without making other changes  (Partitions etc) you cannot stop Backup Exec from taking an overwritable tape from one of your own media sets and moving it to another media set. In other words media sets are just there to manage usage timings they do not enforce that a job can ONLY use media from the set specified in the job.

Media that is new to this specific Backup Exec server (so either btrand new or used by a different media server) can end up in one of the Imported media sets and then used in a similar way to scratch (depending on other settings)

You should only really manually move media into the Scratch or Retired sets leaving Backup Exec to manage it's own media movements between other media sets.

 

 

 

pkh's picture

If the tape is not previous used, then it will end up in the scratch media set automatically.