Reading a tape LTO4 with a Tape Drive HCART3

[issmag]

hi,

how can a tape drive LTO6 (HCART3) read a tape LTO4 (HCART2) ??

It's possible to configure it without chaging drive density ??

thanks in advance for your reply !

[mph999 · Accepted solution]

Not possible unless you change the density of the tape or drive to match.

Martin

[RonCaplinger]

If you just want to READ the tape, you must change the tape drive density to match the cartridge density.  Remember, these density settings are just labels and don't define anything to the tape drive.  They just tell the library that a particular drive is allowed to access tapes of the same density label.  Once you are done reading the HCART2 tape(s), you can set the drive back to the original density label, HCART3.

[mph999]

Sorry,, that was meant to read '.. tape or drive to match'

(not able to edit post for some reason).

Unless the density of the tape and drive matches, NBU will not use them together.

It is annoying, NBU could be more intellegent in ths area, eg, know that a LTO4 tape can be used in LTO6 drive, and at least allow it for restores, if not for backups ... or something along these lines, even if a selectable option.

[issmag]

ok, thanks for your reply RonCaplinger.. is that exactely what i did, and it works very fine.. but i need that the hcart3 drive will be able to read lto4 and lto6 tape at the same time and automaticaly without changing the density evrytime ...!

[RonCaplinger]

The only way to do that is to make LTO4 and LTO6 tapes use the same density label in the barcode rules when tapes are added to NBU.  If the LTO4 tapes are already defined in NBU and have valid data on them, I don't think you can change their density label.

[mph999]

In reply to Rons post ....

The density of the tape or drive can be changed at any time, even if the tape contains data.

If you change the drive, you do need to restart ltid, so changing the density of the tape is probably the better option.

vmchange -new_mt <density> -m <media id>

Where density oulf be hcart2 / hcart3 etc ...  Man page shows all density types available.

[RonCaplinger]

Not sure if something changed, but I previously changed the tape drive density on a couple of tape drives every week from hcart to hcart3 and vice-versa, and never *had* to restart LTID.  We have all LTO4 drives and encrypt all LTO4 tapes, but for the catalog and encryption key manager backups, we use LTO3 tapes since they can't be encrypted and you don't want the catalog stored on an encrypted tape. Since there wasn't much data going to LTO3s compared to the LTO4s, I would vary which tape drive(s) I used for the HCART3 drives week to week so that the drive usage was similar across all drives for the OpsCenter Tape Utilization and Throughput reports.

[Marianne]

... but i need that the hcart3 drive will be able to read lto4 and lto6 tape at the same time and automaticaly without changing the density evrytime ...!

As everyone already said - simply not possible.

Have another look at above posts - Martin and Ron have even explained why this is not possible.