Data Compression on Tape

Question

After upgrading from Legato 7.2 to Networker 7.3.2 the compression doesn't seem to be working. I have Dell PV-122T's using SDLT 160/320 tapes. Prior to the upgrade i was able to fit about 320 to 350 GB of data on a tape. After the upgrade i'm filling the tapes at 160. I'm sure that it is just a check box or something simple. Any assistance is greatly appreciated.

ble1 · Answer

If you're using HW compression nothing in NW should affect that (except device naming, but I assume since you did upgrade that hasn't change). If you're using software compression then that's another story (make sure not to use both!). Have you tried to write to tape 'outside' NW?

dk3 · Answer

How did you update your Networker installation? Did you re-install Networker from scratch or did you keep your Networker settings in nsr-directory?What OS is you backup server running?

One possibility that comes to my mind: If you re-created Networker's device resources during the update and you're running Linux or Unix, make sure you're using compression enabled device paths (e.g. /dev/rmt/0cbn). See tapes' man-page for more details on the meaning of the single path name characters.

chilworth2 · Answer

Don't know if this is an option for you or not, depending on your hardware maintenance, but we had the same issue over time on 200/400gb tapes in an ADIC fastor. Used to fit about 350GB on but this had dwindled to 170GB and less and we were using twice as many tapes as before.
After replacing the tape drive we are back to full capacity on the tapes.
Worth trying if your tape drive is under warranty and easily replaceable.

NetWorker

Data Compression on Tape

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