vxtask(1M) VxVM 3.5 vxtask(1M)
1 Jun 2002
NAME [Toc] [Back]
vxtask - list and administer VERITAS Volume Manager tasks
SYNOPSIS [Toc] [Back]
vxtask abort taskid
vxtask [-ahlpqr ] [-g dg_name [-g dg_name...]] [[-G dg_name] -v volume
[-v volume...]] [-i taskid] list [taskid...]
vxtask pause taskid
vxtask resume taskid
vxtask [-i taskid] set name=value taskid [-c count] [-t time] [-w
wait_interval] [-ln ] monitor [taskid[taskid...]]
DESCRIPTION [Toc] [Back]
The vxtask utility performs basic administrative operations on VERITAS
Volume Manager (VxVM) tasks that are running on the system.
Operations include listing tasks (subject to filtering), modifying the
state of a task (aborting, pausing, resuming), and modifying the rate
of progress of a task.
VERITAS Volume Manager tasks represent long-term operations in
progress on the system. Every task provides the time the operation
started, the size and progress of the operation, and the operation's
state and rate of progress (throttle). You can change the state of a
task, giving coarse-grained control over an operation's progress. For
those operations that support throttling, you can change the rate of
progress of a task, giving more fine-grained control over the task.
The majority of tasks represent I/O being performed to objects.
Operations such as read-writeback recovery for mirrored volumes,
parity recalculation for RAID-5 volumes, volume relayouts, and so
forth, all involve moderate to large amounts of I/O. Tasks that
represent operations that perform I/O directly are referred to as
basic tasks. The task progress information for basic tasks consists of
the starting and ending block of the I/O to be performed and the
offset to which the I/O has currently completed.
Some operations, such as vxrecover and starting RAID-5 volumes, may
require multiple tasks to complete the operation. vxrecover may
determine that many recoveries are required, some that must be
performed serially. Starting a RAID-5 volume requires that its log (if
any) be replayed and cleared, its parity be recalculated (if
necessary), any stale subdisks be resynchronized (if needed), and that
these tasks be performed serially. In these and similar cases, an
overall task is created to keep track of the underlying basic tasks
being performed, and these are known as parent tasks. The progress
information for parent tasks are the total number of subtasks required
to complete the overall operation; the number of subtasks completed;
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and the number of subtasks currently running.
Every task is given a unique task identifier. This is a numeric
identifier for the task that can be specified to the vxtask utility to
specifically identify a single task.
Tasks also contain the following information:
task tag A task's tag is a string that you can specify to make
administration easier. It is usually set by the command that
initiates the task. For most utilities, the -t tasktag
option allows a tag to be specified as a sequence of up to
16 alphanumeric characters.
task type The task's type describes the specific operation that is
being performed. For example, attaching a plex to a volume
results in an atomic copy loop, which is represented by an
ATOMIC_COPY task.
description
Describes the utility operation on whose behalf the I/O is
being performed. For example, both a volume start and a plex
attach can result in an atomic copy loop and thus an
ATOMIC_COPY task. The description of the operation attempts
to disambiguate between tasks that are performing the same
basic work.
object Most tasks are related to a specific object, usually the
volume within which the operation is taking place.
parent Some utilities require multiple operations to fulfill a
request. For example, the vxrecover utility may need to
start many different volumes. In these cases, the subtasks
list their parent.
progress information
Each task has an indication of its starting point and ending
point, and an indication as to what point it has progressed
so far. Combined with the work time, this allows the amount
of time remaining until completion to be estimated for some
tasks.
state Each task has one of three states: RUNNING, PAUSED or
ABORTING.
time Each task notes its starting time and the total amount of
time spent doing work.
KEYWORDS [Toc] [Back]
abort|pause|resume
These three operations request that the specified task
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change its state. pause puts a running task in the paused
state, suspending its operation. resume continues the
operation of a paused task. abort stops the operation of
the specified. In most cases, the operations "back out" in
a manner similar to when an I/O error occurs, reversing as
much as possible what's been done so far.
list List tasks running on the system in one-line summaries. The
value displayed for percentage task progress takes into
account all intermediate steps that are required to
accomplish a specific task.
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 options filter and limit the listed tasks as
follows:
-a Limits the output to tasks in the aborting state.
-g dg_name
Limits the listed tasks to those tasks running on
objects in the diskgroup dg_name.
-G Distinguishes between volumes with the same name
in different diskgroups; see vxintro(1M).
-h Prints tasks hierarchically with a task's child
tasks following the parent task.
-l Prints tasks in long format.
-p Limits the output to tasks in the paused state.
-q Suppresses printing of column headings.
-r Limits the output to tasks in the running state.
-v volume Limits the output to tasks whose object is volume.
Any task meeting any of the criteria specified are printed.
That is, if -v foovol and -p are specified, then any task
operating on foovol or that is paused are printed. If -h
were also specified, then those tasks and all their children
would be listed.
monitor The monitor operation continuously prints information about
a task or group of tasks as the task information changes.
The -l option specifies printing a long listing. The
default is to print one-line listings.
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The monitor command accepts the following options:
-c count Prints count sets of task information, then exits.
-n Monitors not only the tasks specified on the
command line, but also any tasks newly registered
while the program is running.
-t time Exits after time seconds.
-w interval
Prints the string "waiting..." when interval
seconds pass with no output activity.
In addition to printing task information when a task state
changes, output is also generated when the task completes.
When this occurs, the task state is printed as EXITED (see
the OUTPUT section).
set The set operation changes modifiable parameters of a task.
There is only one modifiable parameter for tasks: the slow
attribute, which represents a throttle on the task progress.
The larger the slow value, the slower the progress of the
task and the fewer system resources it consumes in a given
time. (The slow attribute is the same attribute that many
commands, such as vxplex, vxvol and vxrecover, accept.)
OUTPUT [Toc] [Back]
There are two output formats printed by vxtask: a short, one-line
summary format per task, and a long task listing. The short listing
attempts to provide the most used task information for quick perusal,
displaying the following fields from left to right:
1. The task ID for the task.
2. The task ID of the task's parent, if any. If the task has no
parent, this field is left blank.
3. The task type and state, separated by a slash (/). The type
field is a description of the work being performed, such as
ATOMIC COPY for atomic copy I/O and RELAYOUT for an online
relayout operation. The state is a single letter representing
the task state: R for running, P for paused, and K for
aborting. In the special case of the completion of a task
that is being monitored, the state is printed as EXITING.
4. The percentage of the operation that has been completed to
this point.
5. The task's progress information. For basic tasks, this is the
starting offset, ending offset and current offset for the
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operation, separated by slashes (/). For parent tasks, this is
the starting number of child tasks, total number of child
tasks required for the operation to complete, and the number
of child tasks already completed to this point, separated by
slashes, followed by the number of children currently running
in parentheses.
6. A description of the command for which the task is performing
work. This is normally a single word, such as START for a
volume start operation or RELAYOUT for an online relayout,
followed by object names, indicating what the arguments were
for the command. See EXAMPLES below.
The long output format prints all available information for a task,
spanning multiple lines. If more than one task is printed, the output
for different tasks is separated by a single blank line. Each line in
the long output format contains a title for the line, followed by a
colon (:), followed by the information. The possible information
printed for a task includes:
Operation:
A description of the operation on whose behalf the work is
being performed. This is essentially a description of the
command executed along with the VERITAS Volume Manager
objects specified as arguments.
Progress: A description of the progress of the task. The progress is
stated as a percentage of completion, along with the actual
progress values for the task.
Started: The time that the task was started.
Task: General information for the task. The task's ID, followed by
its parent's ID (if any) in parentheses, followed by the
task's state, either RUNNING, PAUSED or ABORTING.
Throttle The throttle value for the task, if applicable.
Type: The task type, describing the work being performed.
Work time:
States how much time has been spent performing the work, and
a rough estimate of the time remaining for the task to
complete.
As a special case, when a task being monitored completes only the
Task: line is printed for the task, with the task state represented by
EXITED.
EXAMPLES [Toc] [Back]
To list all tasks currently running on the system:
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vxtask list
To trace all tasks in the diskgroup foodg that are currently paused,
as well as any tasks with the tag sysstart:
vxtask -g foodg -p -i sysstart list
To list all tasks on the system that are currently paused:
vxtask -p list
To monitor all tasks with the tag myoperation:
vxtask monitor myoperation
To cause all tasks tagged with recovall to exit:
vxtask abort recovall
FILES [Toc] [Back]
/dev/vx/info Used to get task information from the
kernel.
/dev/vx/taskmon Task monitoring device.
SEE ALSO [Toc] [Back]
vxintro(1M), vxplex(1M), vxrecover(1M), vxsd(1M), vxvol(1M)
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