Media Rotation

[adrianmarsh]

Hi All,

I'm running netbackup 7.1

We have a TL4000 tape dual drive.  I have some tapes that sit in a 12 month archive, yet, they may not be touched for several months.

I'd like to setup a job to either:

a) automatically, periodically, transfer that data to a fresh tape

b) test the data on it so we're aware of corruption.

obviously a) is better.

I can't find a job-type for this and thought it would be included by default really.

A.

[Marianne]

No such automated job unless you have the vault option. If not, best to manually select this media and duplicate them to a different pool (to ensure fresh tape is used). See Catalog section of the GUI. Select 'Duplicate' in the drop-down. To test data is also a manual process. Conduct regular restore tests to a temp location.

[mph999]

No need, media is stored correctly will safely hold data for many many years.

It would do no harm to do a test restore or two now and again, but no need to duplicate to new media if storage is only a year.

Martin

[adrianmarsh]

Thanks Marianne,  thats what I figured as much. I kind of think this should be a basic operation. I'll have a look and see if I can script something up. I've not done much scripting in Netbackup in years, but I seem to remember it was quite powerful.  I'll also look at Vault and see if its a feature there.

mph999, thanks for the reply, but I find it quite odd that Symantec would just assume that the media was ok.  It should be good and standard practice to check that backups are retrievable, and for long-term storage verifying the data is something that I think should be part of essential maintenance - I would think that NB should be able to do this automatically, at least to flag up any issues.  You wouldn't want to find out that the restore you're trying to do is corrupt (with all the best preservative best-practice in the world), when you're needing that data.

[mph999]

"mph999, thanks for the reply, but I find it quite odd that Symantec would just assume that the media was ok."

The state of the media is not the responsibility of Symantec.  I would agree that it is a good idea to test - (but you have to balance the idea to test against the details I have posted below.) but it is not the responsibility of the backup software to do this.  That said, we do have the commands to do this, we just don't run them automatically.  (bpverify is the command -0 not quite a restore, but it does read each block) 

You may consider this comment unreasonable (I could understand that ...) but the line has to be drawn somewhere.  So, in the same way Symantec has no responsibility for checking your tapes, we also don't  check your network or operating system or SAN .. Sure, NBU will find the issue if there is one, but it is not for us to monitor the 'health'. 

If you want to monitor the 'real' state of your media - buy something like Storsentry (http://www.quotium.com/prod/storageManagement.php)

However, given that media, if stored as recommened by the manufacturer will last quite happily for 20 - 30 years minimum, I see no point is checking it within a few months, given the simple fact that the worst thing you can do to tape media, is physically move it.

However, this does depend on the tempreature and humidity it is stored at, and moving outside of the recommended values 'could' have a very severe detremental effect on the life period.

Provifing your backup is successful, there are 4 risks to tapes, if they are not stored correctly.

1) The Magnetic coatings used on tapes are chemically 'stable' - that is they won't degrade, but this is highly dependant on operating conditions and storage conditions.

2) The magnetic coatings are 'mechanically' stable - that is, they will stay stuck to the 'base film' of the tape.  Again, this is only true if the tapes are stored correctly.

3) Wound tape packs are 'mechanically' stable.  This is not true if the drives operate in a stop/start fashion.

Given, that for any environment the drive speeds should be checked to ensure that the drives are not stop /starting (shoe-shining) then this ensures the tape pack is kept wound and under 'tension', will minimise 3.

Checking that the environment the tapes are held in is the exact temp and humidity  required for long term storage of the media, as specified by the manufacturer should minimise 1 and 2.

You will notice I am missing the fourth one 

4.  Physically moving them.

Yes, physicall movement of your tapes from archive back to the data center is the biggest risk by a long way.

or put another way ....

The act of transporting your tapes back to site for the test, is the most likely way to cause tape failure.

or put another way ...

There is a greater risk of 'you' making your data unreadable by moving the tapes, than there is of the tapes becoming unreadable via some other 'method'. 

Many of the cases marketed for moving tapes are in fact not all that suitable, so in many cases, with all the best intentions, tapes are not transported correctly which increases the risk even further.

To my knowledge, there is only one tape case on the market that fully protects tapes ... (yes I did a lot of research into this some time back, and pretty much proved everything I have quoted above). 

In my old role, we never moved production tapes, the libraries were locaated off site from the clients  and the media stayed in them, safest place - correct environemntal conditions, safe location, and most importantly no movement of the tapes.  If we needed to move a tape (for example for DR test) it was copied first.

Martin