having a problem with sysback/getting error from sbfwd
Environment: 3.2.5 59H
Description: Customer is issueing the following command to restore data
from a vg on a remote 7331 parallel backup
sysrestore -h \ -v raidvg -d -f vdev2 \
He sees the following messages:
forwarding to raidvg
sbfwd: cannot attach to shared memory for buffer status
sbfwd: permission denied
Action: Explained the message is comming from the sbfwd2 command. A
shared memory segment has been created but is failing on the attach.
The shared memory segment is created when operating against parallel
Customer had huge chunks of shared memory being used by oracle
databases. Customer will try restore when databases are down.
But a work around is:
Customers backup looks like this:
Tape 1 (rmt 2)
Image 1 | Image 2 | Image 3 | Image 4 | Image 5 | Image 6 | Image 7
boot mkinstape dummy sysback rootvg raidvg raid2vg
Tape 2 (rmt 3)
Image 1 | Image 2 | Image 3 |
rootvg raidvg raid2vg
tctl -f /dev/rmt2 rewind
tctl -f /dev/rmt3 rewind
sbdevice -f 5 /dev/rmt2
sbdevice -f 1 /dev/rmt3
sysrestore -h \ -v raidvg -d -n -f vdev2 \
This restored the customer data. He will rewind and reposition to
get data from raid2vg.
This worked because by manually positioning tapes, the sbfwd2 was
never called thus eliminating the need to attach to a shared
memory segment. But the sbread2 which is required to read from the
parallel device will also need to attach to a shared memory
segment. Why the workaround does not fail on the sbread2 is still
But customer will look into his shared memory resources.
Action: Customer called back in and stated that he tried to do the
verify of his parallel backup with the oracle database not running.
This freed up over 100M of shared memory.
But customer still received the sbfwd error message about not being
able to attach to shared memory for buffer status.
Action: Problem is opened with developer.
ON the server system.
chmod ug+s /usr/sbin/sbfwd2
This corrected the problem. When you do a remote backup, you are
sbnet on the server system. The sbfwd2 command will open up a
shared memory segment. It can't do this if it is the sbnet user
on the server. The setuid will correct this and did.
Closing with customer approval
Support Line: having a problem with sysback/getting error from sbfwd ITEM: CG5471L
Dated: December 1996 Category: N/A
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