How to disable HW compression in Tru64

Question

In the AES ASAM thread I mentioned that we're being required to encrypt our data. Our current tape drives don't support HW encryption and we can't replace them so we're going to have to use the AES SW encryption. My concern is the time increase when EAS is enabled. Some of my test backups about doubled in elapsed time because compressasm doesn't work with AES.

Currently HW compression is turned on and I want to turn it off to see if it has an affect. So here's my configuration:

NetWorker V7.3.2 Build 399
NetWorker server: Red Hat Linux V3
NetWorker storage node: Tru64 V5.1B
Jukebox: HP MSL6060 with 4 Ultrium 460 tape drives.

There doesn't appear to be a way within the Jukebox or the tape drives to manually disable compression. I've been in contact with HP Support and they couldn't find a way. With Tru64 you control compression by device name. To enable compression the device name it's /dev/ntape/tape1_d1, to disable it it's /dev/ntape/tape1_d2.

Here's the problem. The 4 tape drives are already defined within NetWorker with compression enabled and I've never tried to define devices myself. This was done by someone else (no longer here of course).

I want to do just a test so can another device be manually added that disables compression and leave the device that has compression?
I have device /dev/ntape/tape1_d1 and I want to add /dev/ntape/tape1_d2. Would that mess things up? Or do I have to delete /dev/ntape/tape_d1? What are the steps?

I'm rather cautious because this backup server is for our mission-critical applications so I have to make sure that backups work.

Thanks,
Vic

dpinink_silva · Answer

Remove d1 and add d2. As the library has 4 drives, I think you can't even add another one without deleting some, and having two paths on the same box for the same physical drive (in Networker) is not something that I would recommend you to do.

Look to see if there's any restrictions about backups that only go to that drive and things like that. These may be the only problems you can have, besides the usual ones

ble1 · Answer

Delete library and disable remaining devices (or delete them too) and reconfigure library using new device names.

vsemaska · Answer

Thanks Daniel & Hrvoje for your replies. Looks like Hrvoje is right, I would have to delete and then readd the jukebox. The NMC doesn't allow you to delete a device within a jukebox. I was wondering if I could delete/add the device via nsradmin? With nsradmin I see the devices listed as:

devices: "rd= .edu:/dev/ntape/tape1_d1",
"rd= .edu:/dev/ntape/tape2_d1",
"rd= .edu:/dev/ntape/tape4_d1",
"rd= .edu:/dev/ntape/tape3_d1";

If I update the devices field with the change that I want to make using nsradmin would that work?

Thanks,
Vic

ble1 · Answer

With nsradmin no, but with jbedit that might be possible (didn't test it).

vsemaska · Answer

Thank Hrvoje, I wasn't aware of the jbedit utility. I think I'll give that a try.

Looking at the manpage for jbedit for adding a drive it states you have to use the -E option to specify the 'data element address of the drive with which the device is associated'. It also says to use utilities relem, changers, sn, sjisn to find this and other information. I used utilities inquire & sn to get this:

inquire:
scsidev@5.0.1:HP Ultrium 2-SCSI F6AW|Tape, /dev/ntape/tape1_d1
S/N: HUL3E00439
ATNN=HP Ultrium 2-SCSI HUL3E00439
WWNN=50060B00001F174A
scsidev@5.0.2:HP Ultrium 2-SCSI F6AW|Tape, /dev/ntape/tape2_d1
S/N: HUP4G00XJU
ATNN=HP Ultrium 2-SCSI HUP4G00XJU
WWNN=50060B00001F650E
scsidev@5.0.3:HP Ultrium 2-SCSI F6AW|Tape, /dev/ntape/tape3_d1
S/N: HUP6J04C3V
ATNN=HP Ultrium 2-SCSI HUP6J04C3V
WWNN=50060B0000FD8AD2
scsidev@5.0.4:HP Ultrium 2-SCSI F6AW|Tape, /dev/ntape/tape4_d1
S/N: HUP5C031JU
ATNN=HP Ultrium 2-SCSI HUP5C031JU
WWNN=50060B000027FE6F

--------------------------------------------------------------------------------

sn:

ATNN=HP Ultrium 2-SCSI HUL3E00439

ATNN=HP Ultrium 2-SCSI HUP4G00XJU

ATNN=HP Ultrium 2-SCSI HUP5C031JU

ATNN=HP Ultrium 2-SCSI HUP6J04C3V

So if I delete tape1_d1 and add tape1_d2 I should use # 480. Is this correct?

Sorry if these are simple questions but again this is an important production systems and I want to make sure I understand as much as possible.

Thanks,
Vic

ble1 · Answer

I delete tape1_d1 and add tape1_d2 I should use #480. Is this correct? Correct.

vsemaska · Answer

OK, was able to delete the tape drive but when I try to add the other name it gives me an error:

csubds5:/> jbedit -d -f /dev/ntape/tape4_d1 -s solegato1
jbedit: Changing device name from /dev/ntape/tape4_d1 to rd= :/dev/ntape/tape4_d1.

csubds5:/> jbedit -a -f /dev/ntape/tape4_d2 -E 483 -s solegato1 -v
setting verbosity level to `1'
jbedit: Changing device name from /dev/ntape/tape4_d2 to rd= :/dev/ntape/tape4_d2.
jbedit: RAP error: Cannot find device `rd= :/dev/ntape/tape4_d2' in 'unconfig device names' resource.

Where is this "unconfig device names" resource?

Thanks,
Vic

ble1 · Answer

mm, those are usually devices listed when scan runs on storage node. You might wish to try it with -F option added. If it doesn't work then you will need to do it via jbconfig.

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How to disable HW compression in Tru64

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