Is it safe to Unfreeze "frozen mpx" media

Hi dear all,

I have huge amount of media with frozen multiplex and frozen status. when I unfreeze a frozen with for example 1G data on it, media status change to active and data on the media will be 0. I dont know data on the mentioned media has expired before or not? does anybody have any idea to re-use frozen media?

Thanks

Tags (2)
12 Replies

Re: Is it safe to Unfreeze "frozen mpx" media

When you unfreeze a tape it will become Active if it was not Full, but will not expire any images - those only get affected when the entire tape is expired and returned to the same pool it came from - usually Scratch but could be a different pool if Scratch pool is not used.

Best regards, Mikhail.
Independent Veritas consultant in Melbourne, Australia

Re: Is it safe to Unfreeze "frozen mpx" media

@shahriar_sadm 

you can see how many active, unexpired images on the tape with this command: 
nbemmcmd -listmedia -mediaid <media-id> 

Unfreezing the tapes will not change any of that. 

You just need to keep an eye on these tapes, because there was a valid reason for NetBackup to freeze it - 
either 3 x I/O errors in 12 hours or a TapeAlert, indicating a hardware error.

Please ensure that you have bptm log folder on master/media or all media servers if you have more than one. 

You can in the meantime check /usr/openv/netbackup/db/errors related to these media id's. 

See this TN: https://www.veritas.com/support/en_US/article.100017681

Re: Is it safe to Unfreeze "frozen mpx" media

Technically, unless you know why the media is frozen, there is a risk if you unfreeze it.

If the media is damaged, and you unfreeze it there is a possibility it could damage the drives - it's fairly rare, but I've seen it happen a few times, in one instance, x6 drives needed replacing because damaged frozen media was repeatedly unfoozen and over time was 'used' in all the drives.

Aside of that, to 're-use' frozen media if you wish to, just unfreeze it - it then reverts back to it's 'normal self' .

Re: Is it safe to Unfreeze "frozen mpx" media

Freeze in netbackup terms, not only freeze the tape for further writes, it also freezes the images on tape, after backups should have expired.

If you unfreeze a tape, Netbackup will expire backups according to their lifetime. If backup lifetime is back in time, unfreezing a media means expiration of all past-due backup on that tape.

On the other hand, if backups are not yet expired, unfreezing a media will not modify those backups.

Re: Is it safe to Unfreeze "frozen mpx" media

I don't think it freezes the images - they still expire in the catalog 'in the background'.  They might not be completly removed, but they pass their expire date as usual.  Hence why if you unfeeze a media it can expire immediately.

I stand to be corrected though ...

Re: Is it safe to Unfreeze "frozen mpx" media

Hi Martin

Agree - behavior may have changed :-)

My understanding is that images are preserved until media is unfrozen, just like when a disk pool is down. So yes, they are likely expired in the backend as you say, but images should be available for restore until media is un-frozen.

/Nicolai

Highlighted

Re: Is it safe to Unfreeze "frozen mpx" media

There are MANY reason for tapes to become "frozen" - and using your detective skills to determine why is one of the important tasks as a NetBackup admin. 

IMHO - only about 25% of the reasons tapes get frozen actually are tape issues 

If a tape is stuck in drive 1, other tapes told to load there, will become frozen.

If a drive has issues and a tape cannot load - it may become frozen.

Excessive head wear can cause read/write errors - and the tapes will get frozen.

 

Frozen stops any images from expiring - but if they have passed their expiration date they will disappear as soon as a clean up runs.

If I determine the tape is good, I make it a practice to run a label process against it to confirm it will load and set up the format correctly.

 

WAY back in the day, there were issues that would take EVERY scratch tape you had and freeze them overnight. Those were the days!

NetBackup 8.1.2 on Solaris 11, writing to DataDomain 9800
duplicating via SLP to LTO5 in SL8500 via ACSLS
Tags (2)

Re: Is it safe to Unfreeze "frozen mpx" media

@shahriar_sadm 

It's been more than a week - have you seen any of our attempts to assist? 

Re: Is it safe to Unfreeze "frozen mpx" media

Dear @Marianne 

Yes, I realized its important to find media freezing root cause, we have many tape alert 4 in the library console it seems hardware issue, finally I contact to library technicals to annually service.

Also based on replies I unfreezed some media with expiration date before 2019 for backups and working fine untill next tape alert.

Thanks for all assists

Re: Is it safe to Unfreeze "frozen mpx" media

What tape alerts are you seeing ...

TBH, tape alerts, 99% of the time prove a library of media issue, but I'm interested :0)

Re: Is it safe to Unfreeze "frozen mpx" media

Hi @mph999 

This is my error: Data cartridge xxxxx has issued a tape alert 4

 

Re: Is it safe to Unfreeze "frozen mpx" media

Best not to unfreeze this media. Tape seems to be bad.
See https://www.veritas.com/content/support/en_US/article.100000622.html
0x04: 'Media Performance Degraded, Data Is At Risk'