eric@hdr.UUCP (Eric J. Johnson) (05/05/88)
I am having trouble reading 9-track tapes that have a blocksize greater than
8192 bytes on my AT&T 3B15 running System V 2.1.1 equipped with a standard
1600 bpi 9-track 1/2 inch tape drive.
Specifically, I have about eighty 1600 bpi tapes, each blocked at 12255 bytes
which need to be loaded. I can read the first 8192 bytes of each block
using dd as follows:
dd if=/dev/rmt/0m ibs=8192 of=tapeout
But, I lose the last part of each block. When I try using the following
dd command:
dd if=/dev/rmt/0m ibs=12255 of=tapeout
dd returns the following message:
dd read error: No such device or address
and I get no data in my output file.
One thing that confused me was that my copy of the TAPE(7) manual says I
can have a buffer size up to 32768 bytes when using the "raw" interface.
I called AT&T Software Support with the dd failure and 32768 byte buffer
limit question and was politely told that yes, the blocksize limit was
indeed 8192 bytes. The 32768 byte number was the record size limit.
Well, now that I've been set straight by talking to Software Support,
does anyone have a work-around/solution to this limitation?
PS: No, the tapes are not available in a smaller blocksize.
--
Eric J. Johnson UUCP: eric@hdr.UUCP || ...!{ihnp4, codas}!hdr!eric
Amperif Corporation. CIS: 72460,11 BIX: ericj
Just a minute, Just a minute, The AE-35 unit will go 100% failure in 72 hours!gwyn@brl-smoke.ARPA (Doug Gwyn ) (05/07/88)
In article <741@hdr.UUCP> eric@hdr.UUCP (Eric J. Johnson) writes: >I am having trouble reading 9-track tapes that have a blocksize greater than >8192 bytes on my AT&T 3B15 running System V 2.1.1 equipped with a standard >1600 bpi 9-track 1/2 inch tape drive. I don't have direct experience with this configuration, but I have heard from usually-reliable sources that the limit is in the magtape controller itself, not in the operating system software. Note that 8K is 4 times larger than the ANSI standard requires. Whoever supplied your 12K tapes should be tasked with providing something that conforms to standards so you can read it. Alternatively you could transcribe the tapes on some other system that supports larger tape block sizes.
friedl@vsi.UUCP (Stephen J. Friedl) (05/07/88)
In article <7849@brl-smoke.ARPA>, gwyn@brl-smoke.ARPA (Doug Gwyn ) writes: > In article <741@hdr.UUCP> eric@hdr.UUCP (Eric J. Johnson) writes: > >I am having trouble reading 9-track tapes that have a blocksize greater than > >8192 bytes on my AT&T 3B15 running System V 2.1.1 equipped with a standard > >1600 bpi 9-track 1/2 inch tape drive. > > I don't have direct experience with this configuration, but I have heard > from usually-reliable sources that the limit is in the magtape controller > itself, not in the operating system software. Considering that AT&T makes both controller hardware and driver software, this does not provide much recourse or alternative :-(. -- Steve Friedl V-Systems, Inc. (714) 545-6442 3B2-kind-of-guy friedl@vsi.com {backbones}!vsi.com!friedl attmail!vsi!friedl