Forum Discussion

avinash59's avatar
avinash59
Level 4
12 years ago

If frozen media can be used again

Hi All,

Need a doubt to be cleared. We are having less amount of tapes in our scratch pool. So, was thinking of reusing a media which will be expiring in the next three days. My main question is, when I gave the command "bpmedialist -summary" in the master server, I can see the list of tapes which will be expiring in the next three days but it is showing like active and non-active category. And also some tapes which are expired already but are in frozen state and some of them are in full multiplexed state. Can anyone suggest me whether I can use the frozen medias?

PS: New to this blog, so please ignore any mistakes

7.5
Backup and Recovery
Managing Backup Devices
Monitoring
NetBackup
Solaris
  • Marianne's avatar
    Marianne
    12 years ago

    The big thing with frozen media is to know why it was frozen.

    There are many reasons why media is frozen. For example:

    3 I/O errors for same media in 12 hours. This is the NBU default as far as media is concerned. There are factors on the I/O path that can cause errors other than media. In this case media can be used again.

    Certain TapeAlerts that will result in media being frozen. This is an indication of bad media. There is a list of these TapeAlerts in NBU Admin Guide II.

    These are just 2 examples. 
    Problem is - if this happened a while ago, there will be nothing in the current logs to tell you why they were frozen. 

    All you can do now is to unfreeze a small number at a time for tapes where images have expired (e.g. 3). Have a look at them to see if physical damage can be seen. If not, put them back in the robot.
    Then keep an eye on these tapes. If backups fail because of I/O errors, check media server bptm log as well as 'Tape Logs' report. On Solaris media server, there may also be something in /var/adm/messages if the OS sees it as hardware error. (Remember that NBU needs the OS to perform I/O.)

    Hope this helps.

  • Marianne's avatar
    Marianne
    Level 6
    12 years ago

    The big thing with frozen media is to know why it was frozen.

    There are many reasons why media is frozen. For example:

    3 I/O errors for same media in 12 hours. This is the NBU default as far as media is concerned. There are factors on the I/O path that can cause errors other than media. In this case media can be used again.

    Certain TapeAlerts that will result in media being frozen. This is an indication of bad media. There is a list of these TapeAlerts in NBU Admin Guide II.

    These are just 2 examples. 
    Problem is - if this happened a while ago, there will be nothing in the current logs to tell you why they were frozen. 

    All you can do now is to unfreeze a small number at a time for tapes where images have expired (e.g. 3). Have a look at them to see if physical damage can be seen. If not, put them back in the robot.
    Then keep an eye on these tapes. If backups fail because of I/O errors, check media server bptm log as well as 'Tape Logs' report. On Solaris media server, there may also be something in /var/adm/messages if the OS sees it as hardware error. (Remember that NBU needs the OS to perform I/O.)

    Hope this helps.

  • mph999's avatar
    mph999
    Level 6
    12 years ago

    Just be aware that tapes may have been frozen due to damage/ fault that cannot be seen.

    We had a case where one or more faulty media actually physically damaged all x6 drives on a site - that's approx £90000 of tape drives, for the sake of a £60 tape ...

    I didn;t have the case persoanlly, but I suspect that frozen media kept being unfrozen, and casued damage as it went through the different drives.

  • Stumpr2's avatar
    Stumpr2
    Level 6
    12 years ago

    Wow,
    I googled for this issue and found a post of mine from 2005 back in the cess_pool days.
     

    I once had a box of bad tapes. I think the box may have been dropped. Tapes are not very forgiving. I also had SAN configuration/firmware problems that also complicated the situation. It took me a couple of months to eventually identify the bad tapes. I did this by creating a pool I called "cess_pool". I placed any frozen tapes into the cess_pool for identification/tracking. I then degaussed the tapes (they were DLT, don't try to degauss LTO's) and relabeled them with bplabel. I then placed the tapes into a "test_pool" and used them for a couple of weeks. I returned any tape that then had an error to the tape manufacturer for a refund.

    cess_pool is a pun, but it may lose humor in other native languages. Here is definition of cesspool

    noun: cesspool
    1. 1.
      an underground container for the temporary storage of liquid waste and sewage.