[comp.sys.mips] Exabyte tape compatibility

han@eemips.tamu.edu (Kyongho Han) (05/05/91)

We have one RC3230 and one RC3240 and both machines have 8mm Exabyte
tape drives.
The Exabyte drive on RC3240 is about one year older than the drive 
on RC3230.
Our problem is 
	We made backup tapes from both drives and thie drive on RC3240
	can read both tapes from RC3240 and RC3230 drives.
	But the drive on RC3230 can read tape from RC3230 only
	and it can not read tape from RC3240.	 
	When we tried to read the RC3240 tape from RC3230 drive,
	we got an error message like this;

	SCSI 4L0: illegal block lenghth 129024, actual=192512
	Tape read error while trying to set up tape
	
We are using the same command for backup on both machines.
/etc/dump 0fubsd /dev/rmt/hc4 126 6000 54000 (filesystem)
We may need to read a tape of one machine from the other drive.
Currently, we can not read tape of RC3240 from Rc3230 drive.
We swapped the tape drive with a new one sent from Mips CSC
but the problem stays as the same.
Are there anybody who has the same problem or who can give me 
some idea ?


han@eemips.tamu.edu
han@ee.tamu.edu

and 

bruce@cs.su.oz (Bruce Janson) (05/05/91)

In article <15793@helios.TAMU.EDU> han@eemips.tamu.edu (Kyongho Han) writes:
>..
>	SCSI 4L0: illegal block lenghth 129024, actual=192512
>	Tape read error while trying to set up tape
>	
>We are using the same command for backup on both machines.
>/etc/dump 0fubsd /dev/rmt/hc4 126 6000 54000 (filesystem)
>..

Yes, we had a possibly related problem here.
We used to do our dumps in big blocks (63KB?).
Then we upgraded some of our machines from 2030's to 3230's and
installed some new operating system releases as well.
Somewhere in there the exabyte drive lost its ability to read
our old backup tapes -- darn.
Apparently the legal maximum blocksize had dropped to 8KB.
Fortunately, we still had an old machine/os configuration
around attached to one of our exabyte drives so we copied all
our backup tapes (ho hum) from the old (big) blocksize to the new
(small) 8KB blocksize.

Today, our backups still use 8KB blocks.
In subsequent os releases MIPS may have changed the blocksize (up)
again but I haven't bothered to check.

So, try changing your (dump) blocksize from 63KB to something smaller.

Cheers,
bruce

Bruce Janson					Email:	bruce@cs.su.oz.au
Basser Department of Computer Science		Phone:	+61-2-692-3272
University of Sydney, N.S.W., 2006, AUSTRALIA	Fax:	+61-2-692-3838