Veritas Volume Manager 5.0 Administrator's Guide (September 2006)

260 Administering volumes
Monitoring and controlling tasks
Managing tasks with vxtask
Note: New tasks take time to be set up, and so may not be immediately available for use
after a command is invoked. Any script that operates on tasks may need to poll for the
existence of a new task.
You can use the vxtask command to administer operations on VxVM tasks that are
running on the system. Operations include listing tasks, modifying the state of a task
(pausing, resuming, aborting) and modifying the rate of progress of a task. For detailed
information about how to use
vxtask, refer to the vxtask(1M) manual page.
VxVM tasks represent long-term operations in progress on the system. Every task gives
information on the time the operation started, the size and progress of the operation, and
the state and rate of progress of the operation. The administrator can change the state of a
task, giving coarse-grained control over the progress of the operation. For those operations
that support it, the rate of progress of the task can be changed, giving more fine-grained
control over the task.
vxtask operations
The vxtask command supports the following operations:
abort Causes the specified task to cease operation. In most cases, the operations
“back out” as if an I/O error occurred, reversing what has been done so far
to the largest extent possible.
list Lists tasks running on the system in one-line summaries. The -l option
prints tasks in long format. The -h option prints tasks hierarchically, with
child tasks following the parent tasks. By default, all tasks running on the
system are printed. If a taskid argument is supplied, the output is limited
to those tasks whose taskid or task tag match taskid. The remaining
arguments are used to filter tasks and limit the tasks actually listed.
monitor Prints information continuously about a task or group of tasks as task
information changes. This allows you to track the progression of tasks.
Specifying -l causes a long listing to be printed. By default, short one-line
listings are printed. In addition to printing task information when a task
state changes, output is also generated when the task completes. When this
occurs, the state of the task is printed as EXITED.
pause Puts a running task in the paused state, causing it to suspend operation.
resume Causes a paused task to continue operation.
set Changes modifiable parameters of a task. Currently, there is only one
modifiable parameter, slow[=iodelay
], which can be used to reduce the
impact that copy operations have on system performance. If
slow is
specified, this introduces a delay between such operations with a default
value for iodelay of 250 milliseconds. The larger the value of iodelay that