[Sunhelp] SUMMARY - Upgraded, now DLT7000 tapes only holding 20Gb

[Bryan Fullerton]

I'm posting a summary mostly so people will stop sending me helpful emails.
Don't get me wrong, they're all good, but I think I've resolved the issue.
Thanks for the messages, they pointed me down the right track and helped me
ask the right questions when I called Sun.

The bulk of the emails I received focused on the st.conf file, which turned
out to be related to the problem.  Apparently, the default device settings for
the Quantum DLT7000 drive (any DLT drive, actually) under Solaris 2.6 identify
it as an "Other Tape Device".  Solaris 7 actually recognizes it as a "DLT
Device".  This is defined in the second field in the st.conf
data-property-name line.

Here's the line from the Solaris 7 st.conf:
#DLT7k-data =   1,0x38,0,0x1D639,4,0x82,0x83,0x84,0x85,2;

And from the Solaris 2.6 st.conf:
#DLT7k-data =   1,0x36,0,0x1D639,4,0x82,0x83,0x84,0x85,2;

I found the actual definitions in /usr/include/sys/mtio.h:
#define MT_ISOTHER      0x36            /* generic other type of tape drive */
#define MT_ISDLT        0x38            /* sun: SCSI DLT tape drive */

In my understanding, this means that under Solaris 7, using different tape
devices (/dev/rmt/...) causes the system to expect different tape capacities
(ie DLT4000/7000 tapes).  Under Solaris 2.6, any of the /dev/rmt devices
would just run at whatever level the drive defaulted to (DLT7000) until EOT
was detected, because there's no predefined length for an "Other Tape Device".

So, from what I can tell (and from what the Sun service rep told me :), the
solution to my problem is to use /dev/rmt/2hbn as my tape device instead of
/dev/rmt/2mbn, which is what I was using previously.

She also recommended I apply the st driver patch, 107460-04, but from the
README it doesn't seem that it resolves any issues directly related to my
problem.  She also sent me a st.conf file, which has slightly different
spacing around the Quantum DLT labelling - not sure if that matters or not.

I won't know for sure if this solves the problem until my next scheduled full
backup (3am Saturday morning), but it certainly makes sense to me.

Thanks for all the help!

Bryan

-- 
Bryan Fullerton                http://www.samurai.com/
Core Competency
Samurai Consulting
Can you feel the Ohmu call?