lctl-get_param(8)

LCTL-GET_PARAM(8)

Lustre Configuration Utilities

LCTL-GET_PARAM(8)

NAME

lctl-get_param - retrieve configuration parameters

DESCRIPTION

Get the value of the named Lustre or LNet PARAMETER on the local node. Parameter names consist of one or more components, separated by a '.' (period). Each component may be specified by plain text or by a wildcard in the glob(7) format. When wildcards are used, more than one parameter may match and be returned. Parameters are often, but not always, of the form obd_name.obd_instance.parameter_name, where obd_name is one of the OBD object types, like ldlm, llite, lmv, lov, mdc, osc, etc., and obd_instance is the name of a Lustre device, like testfs-OST0000, but may be a specific component, or contain wildcards to match some or all devices on the node. Many parameters are readable as a regular user, though some of them are accessible only by the root user for security or implementation reasons. Parameters that match a directory will be shown in blue and symlinks will be shown in cyan.

OPTIONS

-b, --dshbak: Aggregate parameters with wildcards whenever a device number appears in the parameter name. By default --merge is enabled with this option to merge the simplified names. Specify --no-merge if you want the parameter names with wildcards but do not want them to be merged. See lctl-list_param(8) for examples.
-c, --color=auto|always|never: Use one of auto|always|never as the rule of when to apply color. The default is auto which will display color only when the output is to a terminal. The NO_COLOR environment variable is supported.
-F, --classify: Append a '/', '@', or '=' suffix for directories, symlinks, and writeable parameters, respectively. lctl get_param -NF is equivalent to lctl list_param -F.
-H, --header: Prefix each parameter value line with the parameter name, as a header. It also print a line for empty values. It could be useful when wildcards are used and filtering the output.
-l, --links: Follow symlinks while searching for parameters. (enabled by default)
-L, --no-links: Do not follow symlinks while searching for parameters.
-n, --no-name: Print only the parameter value and not parameter name. This may be confusing if multiple parameter names are specified, as the parameters are not identified, and may not be returned in the order that they are specified.
-m, --merge: Merge all parameters that have the same name and value such that only the first one will be shown. Parameters with the same name but different values have the difference highlighted in red.
-M, --no-merge: Do not merge parameters. All parameters will be shown, regardless if they are have the same name and value or not. Duplicate parameters will be printed in yellow, if the values are different the difference will be highlighted in red.
-N, --only-name: Print only matched parameter names and not the values. This is especially useful when using patterns. This option is equivalent to
-o, --module: Include modules params in the parameter search path, meaning that matching module parameters will be shown along side with Lustre parameters.
-p, --path: Print the parameter path instead of the parameter name.
-r, --readable: Print only parameters that are have read permission. Can be used with [-w|--writable] to print parameters that are both readable and writable.
-R, --recursive: Recursively show all of the parameter names below the specified name.
-t, --tunable: Print only tunable parameters. This avoids all parameters containing any of the following:
console|debug_|fail_|force|import|nis|panic_|srpc_sepol|stats|target_obd
-w, --writable: Print only parameters that are have write permission. Can be used with [-r|--readable] to print parameters that are both readable and writable.
-y, --yaml: Some paramters can be presented in a YAML format but are not by default. This will format the parameter data in YAML. If the YAML provides a source: field it can be suppressed with the -n option.

BASH COMPLETION

This command supports bash-completion(1) for tab completion of parameter names available on the local node, with suitable shell and package installation. This can greatly simplify finding which parameters are available, instead of running lctl-list_param(8) repeatedly. To list long options (more descriptive and easily understood) type '--TAB', and to list short options type '-TAB'.

EXAMPLES

Use wildcards to obtain all matching parameters:

# lctl get_param osc.*.max_pages_per_rpc
osc.myth-OST0000-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
osc.myth-OST0001-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
osc.testfs-OST0000-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
osc.testfs-OST0001-osc-ffff8803c9c0f000.max_pages_per_rpc=1024
osc.testfs-OST0002-osc-ffff8803c9c0f000.max_pages_per_rpc=1024

# lctl get_param {mdc,osc}.testfs-*.max_rpcs_in_flight
mdc.testfs-MDT0000-mdc-ffff8803c9c0f000.max_rpcs_in_flight=16
osc.testfs-OST0000-osc-ffff8803c9c0f000.max_rpcs_in_flight=8
osc.testfs-OST0001-osc-ffff8803c9c0f000.max_rpcs_in_flight=8
osc.testfs-OST0002-osc-ffff8803c9c0f000.max_rpcs_in_flight=8

Use -n to obtain output that can be pipped into further commands:

# lctl get_param -n debug
super warning dlmtrace error emerg rpctrace vfstrace config console

# lctl get_param -n devices
0 UP osd-ldiskfs MGS-osd MGS-osd_UUID 4

Some parameters can be shown in a YAML format but require the -y option to do so:

# lctl get_param -y devices
devices:
- index: 0


  status: UP


  type: osd-ldiskfs


  name: MGS-osd


  uuid: MGS-osd_UUID


  refcount: 4

AVAILABILITY

lctl get_param is part of the lustre(7) filesystem package since release 1.7.0