Hardware Compression does not work on HP1537A

[nupdyxa]

I recently acquired a tape storage device in the SUN Enclosure. After connecting to a PC it was recognized as HP1537A. Initially unit had the "Clean" LED steady ON and would not take a tape. After firmware upgrade to the latest available it takes the tape. LT&T tests pass, although some weird messages show up "EEPROM Data not accessible", Media Errors Logged-in", "Insert cleaning cartridge". Cleaning cassette was used multiple times, but message is still there. LT&T compression test indicates that compression is enabled and returns 2.24 as a compression ratio. Now my original problem is that when doing a backup on W2K the comression gets turned off as indicated by LT&T and ratio drops to 1.26 respectively. DIP Switch setting is that #3 is off, all others are on. If unit is power-cycled the comression is enabled once again (until the backup program is launched). I would like to hear from others if there is something wrong with my unit. Is the value of 24GB (with compression) real? I tried native W2K driver 4mmdat.sys as well HP hpsys.dat without much luck. Also tried Veritas Backup software with no luck either. I am using Toshiba Portege 7140 laptop and Adaptec Slim 1480A SCSI Cardbus adapter. Attached are the LT&T produced tickets. First one is for initial LT&T compression test and the second one after the MS Backup disabled the compression.
--Thnx for your help...

[nupdyxa]

Here is the second ticket (after the MS Backup is launched).

[Eugeny Brychkov]

Hello,
I noticed that software applications can turn off compression. And there's a way to force drive not to allow to do it. There was a question here recently, but I do not remember solution - like one dip switch setup change (looks like switch #4 changed off?).
These DAT drives should be cleaned regularly - after each 5 full backups or 20 tape pulling hours. Failing to follow this rule leads to shorten drive life time.
In general I think you should check backup application (in case of NT backup try '/HC:on' key from command line) or force drive not to allow software to change this setting
Eugeny