>I have a 3494 library with 3590 drives, TSM server 5.1.6.3 on AIX 4.3.3
>box, Fibre channel attachment, partitioned 3494 between AIX (TSM) and
>AS/400, have already defined the library as "bws3494", scratch is 302,
>private 300, SHARED LIBRARY is set to "no", Enable3590Library is set to
>yes, I can ping the library which responds to mtlib commands, the 3590
>drives are available and online, but i cant checkin new tape volumes,
>the following error appears, ANR8301E I/O error on library bws3494 (
>op=005c6d37, sense=n/a, cc=00000026 )

Josi - I did some more research, and put together these reference notes:

ANR8301E I/O error on library ______ (OP=________, SENSE=N/A, CC=________).
        Notes: The OP and CC values are hexadecimal.  The CC value is an MTCC_*
        number condition code returned from an I/O control request.  You can
        look them up in the manual "IBM TotalStorage Tape Device Drivers:
        Programming Reference", topic "Error Description for the Library I/O
        Control Requests", near the back of the manual.  The are also listed in
        the /usr/include/sys/mtlibio.h header file that is installed with the
        atldd device driver.

Your cc=00000026 is "Unexpected I/O failure.".
Again, I would look in your AIX Error Log for additional error indications;
and your TSM Activity Log might have additional contextual errors pointing
to a drive.  I would try to pin the error down to some component in the
library.  It's unusual to have just this message if there is a drive issue.
I would check your 3494 for having sufficient cleaning cycles available,
as this might relate to I/O errors on a drive that needs cleaning.  Again,
an 'errpt -a' AIX command may be illuminating.  I would also check your TSM
drive definitions for current validity, and being in an Online=Yes state to
TSM.  If your 3494 or its drivers were recently serviced, watch out for
wacky things: I've had very odd stuff like drives with interchanged serial
numbers/identities in some card pack work.

  Richard Sims, BU