ajb@cornea.mitre.org (Alan J. Broder) (05/09/89)
We have an Exabyte tape drive attached to a Sun-3/180 running 4.0.1 using the scsi-3 interface. We are having big problems. We backed up a whole disk two separate ways. First using tar, we did: tar cvbf 126 /dev/rst9 . then we did a dump of the same disk to ensure that we could recover our files. If you do a tar tvbf 126 /dev/rst9 tar proceeds to list all the files on the tape correctly. However, if you do a tar xvbf 126 /dev/rst9 to restore all the files, tar makes it part of the way through and then just stops. At this point, tar can't be killed, even by root doing a "kill -9". The only way to ever use the tape drive again is to reboot the system. We discovered the exact same thing ocurring with the "dump" tape. Why is it that tar can traverse and list out the contents of the entire tape using "tar tv" but it hangs when doing a "tar xv" ? Has anyone seen a similar problem ? There is clearly a big bug somewhere, perhaps the SCSI driver (we use the scsi driver that comes with the system). Can anyone help ? Alan Broder ajb@cornea.mitre.org <----- use this address The MITRE Corporation
Kemp@DOCKMASTER.NCSC.MIL (05/15/89)
Alan Broder <ajb@cornea.mitre.org> writes that extracting files using tar
from an Exabyte tape drive hangs part way through the tape, but that "tar
tv" will list the contents of the entire tape. I suspect that it works
for listing but not for extracting because extracting (if it's to a local
SCSI disk) causes more SCSI bus activity.
We have been using Exabytes for about a month now, and I have also had
problems with permanent hangs. The installation instructions for our
APUNIX software says to disable SCSI disconnects by editing the file
/sys/sundev/sc_conf.c:
/* scsi disconnect/reconnect global enable flag */
int scsi_disre_enable = 0;
The default value of 1 allows SCSI devices to disconnect and reconnect to
the SCSI bus. According to the instructions, "You may be able to run with
disconnects enabled depending on what other devices you have attached to
the SCSI bus."
I first tried building the kernel with disconnects disabled, but when the
swap partition and everything else are on SCSI disks, the whole system
hangs while the tape is rewinding. I then tried enabling disconnects, and
got the same symptoms as Alan: the process using the Exabyte would hang
permanently, until a reboot. We are now using the lesser of the two
evils: temporary hangs with disconnects disabled.
This is on a Sun-4 running 4.0.1, which uses what Sun calls the sw
("SCSI-weird") driver. How apropos. Let's hope the new "Corporate SCSI"
driver works a little better than this.
Dave Kemp <Kemp@dockmaster.ncsc.mil>
P.S. Some Sun-spotter asked something like "How about that cute little
Sparcstation-1". All I can say is BLETCH. Frog Design laid an egg on
that one. The dimpled front looks just like a big Band-Aid (tm). I don't
want a computer that shouts LOOK AT ME - I'M A PIECE OF OFFICE ART! If
only they had just shrunk the 3/60 cabinet down to 16"x16", now that would
have been a nice, quiet, classic design.