NAME
st_fail_overruns — determines whether variable block mode read requests smaller than the physical record size will fail
VALUES
Allowed values
0 (off)
or non-zero (on)
Recommended values
0 (off)
or non-zero (on)
DESCRIPTION
This tunable determines whether variable block mode read requests through the
stape driver, that are smaller than the physical record size, will fail with
the error
EFBIG.
For example, if a variable block mode read request of 32K was sent to a tape
device with media of record size 64K, the entire record's data would not be
returned to the host.
If the tunable was set to
non-zero (on),
the read would be returned as failed with error
EFBIG.
If the tunable were set to
0 (off),
the read request would be returned as successful with a return value
equal to the number of bytes read.
Who Is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect on the next boot.
When Should the Tunable Be Turned On?
If you want the stape driver to fail overrun variable block mode reads
to tape as some applications require.
What Are the Side Effects of Turning the Tunable On?
Variable block mode read requests through the stape driver that are smaller than
the record fail with
EFBIG.
When Should the Tunable Be Turned Off?
If you want the stape driver to handle an overrun read as a successful
read, forcing you to retry the read with the proper request size.
This is the behavior most backup software expects.
What Are the Side Effects of Turning the Tunable Off?
The return value of the read must be checked to verify the number of bytes
read equals the amount of data requested on all variable block mode reads.
What Other Tunables Should Be Changed at the Same Time?
None.
WARNINGS
All HP-UX kernel tunable parameters are release specific.
This parameter may be removed or have its meaning changed in future
releases of HP-UX.
Installation of optional kernel software, from HP or other vendors,
may cause changes to tunable parameter values. After installation,
some tunable parameters may no longer be at the default or
recommended values. For information about the effects of
installation on tunable values, consult the documentation
for the kernel software being installed.
For information about optional kernel software that was
factory installed on your system, see
HP-UX Release Notes
at
http://docs.hp.com.
AUTHOR
st_fail_overruns
was developed by HP.
