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158 Administering dynamic multipathing (DMP)
Administering DMP using vxdmpadm
The following example shows how to disable I/O throttling for the paths to the
enclosure enc0:
# vxdmpadm setattr enclosure enc0 recoveryoption=nothrottle
The vxdmpadm setattr command can be used to enable I/O throttling on the
paths to a specified enclosure, disk array name, or type of array:
# vxdmpadm setattr \
{enclosure enc-name|arrayname name|arraytype type}\
recoveryoption=throttle {iotimeout=seconds|queuedepth=n}
If the iotimeout attribute is specified, its argument specifies the time in
seconds that DMP waits for an outstanding I/O request to succeed before
invoking I/O throttling on the path. The default value of iotimeout is 10
seconds. Setting
iotimeout to a larger value potentially causes more I/O
requests to become queued up in the SCSI driver before I/O throttling is invoked.
If the queuedepth attribute is specified, its argument specifies the number of I/O
requests that can be outstanding on a path before DMP invokes I/O throttling.
The default value of queuedepth is 40. Setting queuedepth to a larger value
allows more I/O requests to become queued up in the SCSI driver before I/O
throttling is invoked.
Note: The iotimeout and queuedepth attributes are mutually exclusive.
The following example sets the value of
iotimeout to 60 seconds for the
enclosure enc0:
# vxdmpadm setattr enclosure enc0 recoveryoption=throttle \
iotimeout=60
The next example sets the value of queuedepth to 30 for the paths to all
Active/Active arrays:
# vxdmpadm setattr arraytype A/A recoveryoption=throttle \
queuedepth=30
Specifying recoveryoption=default resets I/O throttling to the default settings
corresponding to
recoveryoption=throttle iotimeout=10, for example:
# vxdmpadm setattr arraytype A/A recoveryoption=default
This command also has the effect of configuring a fixed-retry limit of 30 on the
paths.
See “Configuring the response to I/O failures” on page 156 for details.
Note: The I/O throttling settings are persistent across reboots of the system.