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157Administering dynamic multipathing (DMP)
Administering DMP using vxdmpadm
The following example configures time-bound recovery for the enclosure enc0,
and sets the value of
iotimeout to 60 seconds:
# vxdmpadm setattr enclosure enc0 recoveryoption=timebound \
iotimeout=60
The next example sets a fixed-retry limit of 10 for the paths to all Active/Active
arrays:
# vxdmpadm setattr arraytype A/A recoveryoption=fixedretry \
retrycount=10
Specifying recoveryoption=default resets DMP to the default settings
corresponding to
recoveryoption=fixedretry retrycount=30, for example:
# vxdmpadm setattr arraytype A/A recoveryoption=default
This command also has the effect of configuring I/O throttling with an I/O
timeout value of 10 seconds on the paths.
See “Configuring the I/O throttling mechanism” on page 157 for details.
Note: The response to I/O failure settings is persistent across reboots of the
system.
Configuring the I/O throttling mechanism
By default, II/O throttling is turned on for all paths with DMP configured to wait
for a maximum of 10 seconds for outstanding I/O requests to succeed. To display
the current settings for I/O throttling that are applied to the paths to an
enclosure, array name or array type, use the
vxdmpadm getattr command:
# vxdmpadm getattr \
{enclosure enc-name|arrayname name|arraytype type}\
recoveryoption
See “Displaying recoveryoption values” on page 159 for more information.
The following example displays the I/O throttling setting for the paths to the
enclosure enc0:
# vxdmpadm getattr enclosure enc0 recoveryoption
If enabled, I/O throttling imposes a small overhead on CPU and memory usage
because of the activity of the statistics-gathering daemon. If I/O throttling is
disabled, the daemon no longer collects statistics, and remains inactive until I/O
throttling is re-enabled.
To turn off I/O throttling, use the following form of the
vxdmpadm setattr
command:
# vxdmpadm setattr \
{enclosure enc-name|arrayname name|arraytype type}\
recoveryoption=nothrottle