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NAME

na_priority - commands for managing priority resources.

SYNOPSIS

priority command argument ...

DESCRIPTION

The priority family of commands manages resouce policies for the appliance. These policies are especially applicable on a heavily loaded appliance where resources are limited. Others, such as buffer cache policy, are also of value in a more general environment.

Administrators may set various priority policies, including the following:

The relative priority of work associated with a volume (see na_vol.1)

For a given volume, the relative priority of system-related operations (e.g. snapmirror transfers) compared to user-related operations.

The buffer cache policy to be used for a volume.

A default priority policy is also defined, used when a volume does not have a specific policy assigned to it.

USAGE

priority on | off

Globally enables or disables priority management on the appliance. Use the priority show command to display whether priority management is currently enabled on the appliance. See also the subcommand priority set enabled_components which allows selected priority components to be active after priority on is used.
Note: priority on must be used for priority policies to be active.

priority set volume volname option=value [option=value ...]

The priority set volume command manages the priority policy for the volume volname. The following options may be specified:

service
Set the service for the volume to value, which may be on or off. When first setting the priority policy for a volume the service is automatically set to on, unless it is explicitly disabled by setting to off. The off value may also be used subsequently to disable the explicit policy for the volume, while still preserving custom values. The policy for the volume may be permanently deleted using priority delete volume.

level Set the priority level for operations sent to the volume when compared to other volumes. The value may be one of VeryHigh, High, Medium, Low or VeryLow. A volume with a higher priority level will receive more resources than a volume with lower resources. This option sets derived values of scheduling (CPU), concurrent disk IO limit and NVLOG usage for the volume, based on the settings of other volumes in the aggregate.

system Set the relative priority for system related operations (such as snapmirror transfers) sent to the volume compared to user operations sent to the volume. The value may be one of VeryHigh, High, Medium, Low or VeryLow, or a numeric percentage from 1 to 100%.

cache Set the buffer cache policy to use for the volume. Legal values are keep, meaning try to cache buffers if possible; reuse, meaninng buffers may be immediately reused; and default, meaning that the system default policy should be used.

priority set default option=value [option=value ...]

The priority set default command manages the default priority policy, which is applied to volumes without any specific priority policy. The following options may be specified:

level Set the priority level for operations sent to the volume when compared to other volumes. The value may be one of VeryHigh, High, Medium, Low or VeryLow. A volume with a higher priority level will receive more resources than a volume with lower resources.

system Set the relative priority for system related operations (such as snapmirror transfers) sent to the volume compared to user operations sent to the volume. The value may be one of VeryHigh, High, Medium, Low or VeryLow, or a numeric percentage from 1 to 100%.

priority set option=value

Set global priority policy options. The following options may be set:

io_concurrency
Sets the limit on the average number of concurrent suspended operations per disk for each volume. The allowed number of suspended operations for a specific volume is determined by the IO concurrency setting, the number of disks in the enclosing aggregate for the volume and the type of disk. The value default restores the IO concurrency to its initial default.

enabled_components
Sets the enabled priority components. Only the specified components are activated. Allowed values are all or cache. The default is all.
Note: priority on must be used to activate priority policies in general.

priority show
Display global priority setting options, including whether or not priority is enabled.

priority show default [-v]
Display the default priority policy. The default priority policy is used when no specific priority policy has been specified. If the -v (verbose) option is used then more detailed output will be shown.

priority show volume [-v] [volname]
Display the priority policy configuration for volume volname. If no volume name is given then the priority policy configurations for all volumes are shown.
If the -v (verbose) option is used then more detailed output will be shown for options available at the current priority level.

priority delete volume volname
Delete priority policy information for the volume named volname.

CLUSTER CONSIDERATIONS

When a clustered system is in failover mode priority policy is merged from both cluster nodes to form a combined policy.

EXAMPLES

priority set volume prodvol level=high system=low

Set the priority scheduling policy for volume prod_vol to high compared to other volumes. Also prioritize system operations for the volume low compared to user operations on the same volume. These options are also enabled by this operation if priority on has been previous issued.

priority delete volume prodvol

Delete any specific priority policy for volume prodvol. In this case the default policy is applied for the volume.

priority on
priority set enabled_components=cache
priority set volume logvol cache=reuse

Set the cache policy for logvol to not cache data. Only the cache component of priority is enabled.

SEE ALSO

na_vol (1), na_snapmirror (1),


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