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J_H_Is_gone's avatar
J_H_Is_gone
Level 6
16 years ago
Solved

What a frozen tape really is ?

Can anybody chime in here and clear up my missunderstanding.

I thought a "frozen" tape meant that the images on the tape would not expire, that it would keep its assigned date, and not be used for backups.

that a "suspend" tape would not be used for backups but once all images on it expired the assigned date would be cleared and the tape made available for backups.


My confusion - I had a frozen tape
It still shows it has an assigned date
the tape is not being chosen for backups
but
all my images on the tape expired - so I had to import the tape to see what was on it.

Am I just misunderstanding what a "frozen" tape is or is there something wrong?
7.1.x and Earlier
Backup and Recovery
NetBackup
  • petejb's avatar
    petejb
    16 years ago
    Hi,

    Frozen media is not used by Netbackup for backups (you can restore though) as it has either been frozen for a reason by the system, or it has been manually frozen (I am guessing you have done this based on how you think it behaves).

    You can manually freeze media as a way for Netbackup not to use tapes, but lots of other ways exist. In your post you are correct on how frozen media will behave (apart from the images portion) but your confusion might be why you have a frozen tape.

    Media can be frozen for a number of reasons normally "Media" Issues.
    These are normally write errors, media positioning errors or allocation errors. In some cases it can be media mis-match errors (i.e. The barcode does not match the electronic version on the tape, the type of tape does not match how you have it defined etc). It has Netbackup Catalog data on it, is write protected etc). The list is very big I am afraid.

    I think Technotes exist for the reasons and they are pretty extensive. The above are from personal experiance.

    The bottom line is:
    If you have frozen media they will not be used for backups (Netbackup marked them in the Media Database for Saftey reasons as it thinks a problem exists)

    They may have an allocated time and date (as that's when Netbackup went to use it) but NO images as it did not get as far as putting any data on the tape.

    If you have images on the tape, it is more than likely that you experianced some media write/positioning errors. but remember just the MEDIA has been Frozen, not the images on the media so they will expire as they would on a "good" tape.

    If you want to keep the images safe as they were written with the wrong retension or you have other reasons you can use bpexpdate to change the retensions in the database for the images.

    If you only have just one frozen tape, it is quite likely it is just a "dodgy" tape or perhaps its as simple as the write protect tab is on.

    Hope it helps.

     

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  • petejb's avatar
    petejb
    Level 2
    16 years ago
    Hi,

    Frozen media is not used by Netbackup for backups (you can restore though) as it has either been frozen for a reason by the system, or it has been manually frozen (I am guessing you have done this based on how you think it behaves).

    You can manually freeze media as a way for Netbackup not to use tapes, but lots of other ways exist. In your post you are correct on how frozen media will behave (apart from the images portion) but your confusion might be why you have a frozen tape.

    Media can be frozen for a number of reasons normally "Media" Issues.
    These are normally write errors, media positioning errors or allocation errors. In some cases it can be media mis-match errors (i.e. The barcode does not match the electronic version on the tape, the type of tape does not match how you have it defined etc). It has Netbackup Catalog data on it, is write protected etc). The list is very big I am afraid.

    I think Technotes exist for the reasons and they are pretty extensive. The above are from personal experiance.

    The bottom line is:
    If you have frozen media they will not be used for backups (Netbackup marked them in the Media Database for Saftey reasons as it thinks a problem exists)

    They may have an allocated time and date (as that's when Netbackup went to use it) but NO images as it did not get as far as putting any data on the tape.

    If you have images on the tape, it is more than likely that you experianced some media write/positioning errors. but remember just the MEDIA has been Frozen, not the images on the media so they will expire as they would on a "good" tape.

    If you want to keep the images safe as they were written with the wrong retension or you have other reasons you can use bpexpdate to change the retensions in the database for the images.

    If you only have just one frozen tape, it is quite likely it is just a "dodgy" tape or perhaps its as simple as the write protect tab is on.

    Hope it helps.

     

  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    16 years ago
    I think I was under the same impression as yourself, that the images would remain ad-infinitum. But, having read & re-read & read again the Admin Guide, I think it's that same old chestnut with confusion between media & images:

    "...
    A frozen volume is unavailable for future backups. A frozen volume never expires, even after the retention period ends for all backups on the media. The media ID is never deleted from the NetBackup media catalog, and it remains assigned to NetBackup.
    A frozen volume is available for restores. If the backups have expired, you must import the backups first.
    ..."

    So, yeah, the volume always remains assigned & will not be overwritten, but the images will expire & need importing.

    It's the same again, essentially, for suspended media:

    "...
    You cannot use a suspended volume for backups until retention periods for all backups on it have expired. At that time, NetBackup deletes the suspended volume from the NetBackup media catalog and unassigns it from NetBackup.
    A suspended volume is available for restores. If the backups have expired, you must import the backups first.
    ..."

  • Marianne's avatar
    Marianne
    Level 6
    16 years ago
    Hi Judy

    Extract from Admin Guide I: Media -> Volume Operations
    A frozen volume is unavailable for future backups. A frozen volume never expires, even after the retention period ends for all backups on the media. The media ID is never deleted from the NetBackup media catalog, and it remains assigned to NetBackup.
  • Dimitris_Peppas's avatar
    Dimitris_Peppas
    Level 4
    16 years ago
     there is a significant difference between frozen and suspended.

    Expired media cannot be written to even after expiration. A frozen media, when expired will show (in bpmedialist) will show up as EXPIRED FROZEN. So, if needed, you can restore the data,even after expiration by importing it.

    A suspended media will not allow any backups to be written to it UNTIL it expires, at which point it will become un-assigned. If it;s written to, it cannot be imported



  • Andy_Welburn's avatar
    Andy_Welburn
    Level 6
    16 years ago
    "It's the same again, essentially, for suspended media:" I'm actually referring to the general statements about importing expired images on either frozen or suspended media & was not implying in any way shape or form that frozen & suspended media were 'the same'  - just thought I'd clarify that ;)

    Talking of clarification, can you clarify:

    1) "Expired media cannot be written to even after expiration" (I presume you actually mean frozen media in this instance?) and especially
    2) "If it;s written to, it cannot be imported"

    ? Ta.
  • Dimitris_Peppas's avatar
    Dimitris_Peppas
    Level 4
    16 years ago
     1) "Expired media cannot be written to even after expiration" (I presume you actually mean frozen media in this instance?)
    Frozen media is never de-assigned, and cannot be written to, so even if the "image" expired, the data is still on the tape (if it's not damaged) and can be imported to the database and restored.


    2) "If it;s written to, it cannot be imported"
    If a tape that previously had data and has expired is written again from the beggining (when it's scratch it's written from the start), then you cannot recover the data (that has been overwritten, of course).
    I think it IS possible to restore data that has not been overwritten as long as you do not overwrite all the fragments.

    BR,
    DP 
  • J_H_Is_gone's avatar
    J_H_Is_gone
    Level 6
    16 years ago
    It's always in the the details.

    I was doing multiple restores from the same tape.
    A restore was in progress when it was time for me to go home, and I knew the images on the tape would expire that night.
    So I froze the tape - as it was still in the library- because I did not want backups that night to use it.
    When I came in the next morning all my images on the tape had expired.
    I guess I had just never run so close to images expiring on me before.
    And I foolishly thought the tape would be good the next morning - I did not want to extend the expiration date, just wanted to finish the restores.
    So then I had to import it to get the last restore off of it.
    So much for trying to do it the easy way!
    Next time I think it will expire on me I will extend the expiration date of the images.  Less work then importing!

    Again, thanks for all the input - and Thanks Andy for saying I was not the only person who thought this way.

    I am giving petejb the solution as he was the first to say:
    If you have images on the tape, .......but remember just the MEDIA has been Frozen, not the images on the media so they will expire as they would on a "good" tape.