Tunables can be modified by editing the file /kernel/drv/vxio.conf
for most VxVM tunables, or by editing the file /kernel/drv/vxdmp.conf
for DMP tunables. The system must be shut down and rebooted for the change to take effect.
Caution
If you modify /kernel/drv/vxio.conf
or /kernel/drv/vxdmp.conf
, make a backup copy of the file.
For example, a single entry has been added to the end of the following /kernel/drv/vxio.conf
file to change the value of vol_tunable to 5000:
name="vxio" parent="pseudo" instance=0
Caution
Do not edit the configuration file for the vxspec
driver, /kernel/drv/vxspec.conf
.
You can use the prtconf
-vP
command to display the current values of the tunables. All VxVM tunables that you specify in /kernel/drv/vxio.conf
and /kernel/drv/vxdmp.conf
are listed in the output under the "System properties." heading for the vxio
and vxdmp
drivers. All unchanged tunables are listed with their default values under the "Driver properties" heading. The following sample output shows the new value for vol_tunable in hexadecimal:
name <voldrl_max_seq_dirty> length <4>
For more information, see the prtconf
(1M) and driver.conf
(4) manual pages.
Most DMP tunables may be set online (without requiring a reboot) by using the vxdmpadm
command as shown here:
# vxdmpadm settune
dmp_tunable=value
The values of these tunables can be displayed by using this command:
# vxdmpadm gettune
[dmp_tunable]
The vxdmpadm
command also allows you to configure how DMP responds to I/O errors at the level of the paths to individual arrays. See Administering DMP using vxdmpadm for details.