HP-UX Reference (11i v2 07/12) - 5 Miscellaneous (vol 9)

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st_san_safe(5) st_san_safe(5)
(Tunable Kernel Parameters)
NAME
st_san_safe - determines whether access to stape device special files without the no-rewind-on-close option
are allowed
VALUES
Failsafe
0 (off)
Default
1 (on)
Allowed values
0 (off)
any positive integer (on)
Recommended values
0 (off) or 1 (on)
DESCRIPTION
This tunable notifies the stape driver whether it should allow access to device special files without the no-
rewind-on-close option. With this tunable
on, the stape driver will fail any open on a stape device special
file without the no-rewind-on-close option (i.e.,
/dev/rmt/1m or /dev/rmt/1mb ) with a status of [EIN-
VAL].
The
st_san_safe tunable allows the safe sharing of tape devices in SAN tape backup solution
configurations. The disabling of device special files without no-rewind-on-close in a SAN tape backup solu-
tion configuration prevents the accidental sending of a rewind command on close from HP-UX systems via
standard tape commands like mt(1) which would corrupt a backup in process.
Who Is Expected to Change This Tunable?
Anyone.
Restrictions on Changing
Changes to this tunable take effect immediately.
When Should the Tunable Be Turned On?
This tunable should be turned on if the system is going to be used in a SAN tape backup solution
configuration.
What Are the Side Effects of Turning the Tunable On?
The stape driver will fail any open to a stape device special file that does not have the no-rewind-on-close
option with a status of [EINVAL]. This behavior prevents the usage of any stape device special file without
the no-rewind-on-close option.
When Should the Tunable Be Turned Off?
If the system is not part of a SAN tape backup solution configuration or the system utilizes frecover(1M),
this tunable should be turned
off. frecover(1M) will not function unless it has access to device special files
without the no-rewind-on-close option.
What Are the Side Effects of Turning the Tunable Off?
A rewind may be issued from this system accidentally on close possibly corrupting a backup being issued
from another system on the SAN.
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 parame-
ter 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
442 Hewlett-Packard Company − 1 − HP-UX 11i Version 2: December 2007 Update