mClock configuration options

Learn the different mClock configuration options.

Following are the list of mClock configuration options:

osd_mclock_profile

Description

It sets the type of mClock profile to provide the quality of service (QoS) based on operations that belong to different classes, such as background recovery, backfill, pg scrub, snap trim, client op, and pg deletion.

On enabling a built-in profile, the lower-level mClock resource control parameters, that is reservation, weight, and limit, and some Ceph configuration parameters are set transparently. This does not apply for the custom profile.

Type: String
Default: balanced
Valid choices: balanced, high_recovery_ops, high_client_ops, custom

osd_mclock_max_capacity_iops_hdd

Description: It sets a maximum random write IOPS capacity, at 4 KiB block size, to consider per OSD for rotational media. Contributes in QoS calculations when enabling a dmclock profile. It is only considered for osd_op_queue = mclock_scheduler
Type: Float
Default: 315.0

osd_mclock_max_capacity_iops_ssd

Description: It sets a maximum random write IOPS capacity, at 4 KiB block size, to consider per OSD for solid-state media.
Type: Float
Default: 21500.0

osd_mclock_cost_per_byte_usec_ssd

Description: Indicates cost per byte in microseconds to consider per OSD for SDDs. Contributes in QoS calculations when enabling a dmclock profile. It is only considered for osd_op_queue = mclock_scheduler
Type: Float
Default: 0.011

osd_mclock_max_sequential_bandwidth_hdd

Description: Indicates the maximum sequential bandwidth in bytes to consider for an OSD whose underlying device type is rotational media. This option is considered by the mclock scheduler to derive the cost factor to be used in QoS calculations. Only considered for osd_op_queue = mclock_scheduler
Type: Size
Default: 150_M

osd_mclock_max_sequential_bandwidth_ssd

Description: Indicates the maximum sequential bandwidth in bytes to consider for an OSD whose underlying device type is solid-state media. This is considered by the mclock scheduler to derive the cost factor to be used in QoS calculations. Only considered for osd_op_queue = mclock_scheduler
Type: Size
Default: 1200_M

osd_mclock_force_run_benchmark_on_init

Description: This force-runs the OSD benchmark on OSD initialization or boot-up.
Type: Boolean
Default: False
See also: osd_mclock_max_capacity_iops_hdd, osd_mclock_max_capacity_iops_ssd

osd_mclock_skip_benchmark

Description: Setting this option skips the OSD benchmark on OSD initialization or boot-up.
Type: Boolean
Default: False
See also: osd_mclock_max_capacity_iops_hdd, osd_mclock_max_capacity_iops_ssd

osd_mclock_override_recovery_settings

Description: Setting this option enables the override of the recovery or backfill limits for the mClock scheduler as defined by the osd_recovery_max_active_hdd, osd_recovery_max_active_ssd, and osd_max_backfills options.
Type: Boolean
Default: False
See also: osd_recovery_max_active_hdd, osd_recovery_max_active_ssd, osd_max_backfills

osd_mclock_iops_capacity_threshold_hdd

Description: It indicates the threshold IOPS capacity, at 4 KiB block size, beyond which to ignore the Ceph OSD bench results for an OSD for HDDs.
Type: Float
Default: 500.0

osd_mclock_iops_capacity_threshold_ssd

Description: It indicates the threshold IOPS capacity, at 4 KiB block size, beyond which to ignore the Ceph OSD bench results for an OSD for SSDs.
Type: Float
Default: 80000.0

osd_mclock_scheduler_client_res

Description: It is the default I/O proportion that is reserved for each client. The default value of 0 specifies the lowest possible reservation. Any value greater than 0 and up to 1.0 specifies the minimum IO proportion to reserve for each client in terms of a fraction of the OSD’s maximum IOPS capacity.
Type: Float
Default: 0
min: 0
max: 1.0

osd_mclock_scheduler_client_wgt

Description: It is the default I/O share for each client over reservation.
Type: Unsigned integer
Default: 1

osd_mclock_scheduler_client_lim

Description: It is the default I/O limit for each client over reservation. The default value of 0 specifies no limit enforcement, which means each client can use the maximum possible IOPS capacity of the OSD. Any value greater than 0 and up to 1.0 specifies the upper IO limit over reservation that each client receives in terms of a fraction of the OSD’s maximum IOPS capacity.
Type: Float
Default: 0
min: 0
max: 1.0

osd_mclock_scheduler_background_recovery_res

Description: It is the default I/O proportion reserved for background recovery. The default value of 0 specifies the lowest possible reservation. Any value greater than 0 and up to 1.0 specifies the minimum IO proportion to reserve for background recovery operations which is in terms of a fraction of the OSD’s maximum IOPS capacity.
Type: Float
Default: 0
min: 0
max: 1.0

osd_mclock_scheduler_background_recovery_wgt

Description: It indicates the I/O share for each background recovery over reservation.
Type: Unsigned integer
Default: 1

osd_mclock_scheduler_background_recovery_lim

Description: It indicates the I/O limit for background recovery over reservation. The default value of 0 specifies no limit enforcement, which means background recovery operation can use the maximum possible IOPS capacity of the OSD. Any value greater than 0 and up to 1.0 specifies the upper IO limit over reservation that background recovery operation receives in terms of a fraction of the OSD’s maximum IOPS capacity.
Type: Float
Default: 0
min: 0
max: 1.0

osd_mclock_scheduler_background_best_effort_res

Description: It indicates the default I/O proportion that is reserved for background best_effort. The default value of 0 specifies the lowest possible reservation. Any value greater than 0 and up to 1.0 specifies the minimum IO proportion to reserve for background best_effort operations in terms of a fraction of the OSD’s maximum IOPS capacity.
Type: Float
Default: 0
min: 0
max: 1.0

osd_mclock_scheduler_background_best_effort_wgt

Description: It indicates the I/O share for each background best_effort over reservation.
Type: Unsigned integer
Default: 1

osd_mclock_scheduler_background_best_effort_lim

Description: It indicates the I/O limit for background best_effort over reservation. The default value of 0 specifies no limit enforcement, which means background best_effort operation can use the maximum IOPS capacity of the OSD. Any value greater than 0 and up to 1.0 specifies the upper IO limit over reservation that background best_effort operation receives in terms of a fraction of the OSD’s maximum IOPS capacity.
Type: float
Default: 0
min: 0
max: 1.0

Reference

For more details about this osd_op_queue option, see Object Storage Daemon (OSD) configuration options .