ALTER TIER - Kinetica Docs

The size & eviction thresholds of storage tiers can be modified, applying the change to individually specified ranks or all ranks at once. Tier settings can be viewed with SHOW SYSTEM PROPERTIES.

ALTER TIER Syntax

ALTER TIER <tier name>
WITH OPTIONS (<tier property name> = <tier property value>[,...])

Parameters

Name of the storage tier to alter.

Name	Description
`VRAM`	Alter the VRAM tier.
`RAM`	Alter the RAM tier.
`DISK[n]`	Alter the specified disk tier.
`PERSIST`	Alter the persist tier.
`COLD[n]`	Alter the specified cold storage tier.

WITH OPTIONS

Optional indicator that a comma-delimited list of tier property name / tier property value assignments will follow.

Property	Description
`capacity`	Size, in bytes, of a rank in this tier; for RAM, disk, & persist tiers.
`high_watermark`	High watermark eviction threshold for a rank in this tier; for VRAM, RAM, disk, & persist tiers.
`low_watermark`	Low watermark eviction threshold for a rank in this tier; for VRAM, RAM, disk, & persist tiers.
`wait_timeout`	Timeout, in seconds, for reading from or writing to this tier; for cold storage tiers.
`persist`	Whether to save this change to the database configuration so that it will stay in effect after a database restart; default is `true`.
`rank`	Specific rank in this tier to apply the change to; default is to apply the change to all ranks in the tier.

Examples

To alter the capacity of the RAM tier on rank 0 to 500MB temporarily (until the database is restarted):

ALTER TIER Capacity on a Rank Temporarily Example

ALTER TIER ram
WITH OPTIONS
(
	'capacity' = '500000000',
	'rank' = 0,
	'persist' = false
)

To show the change took effect:

SHOW Tier Capacity on a Rank Example

SHOW SYSTEM PROPERTIES
WITH OPTIONS ('properties' = 'conf.tier.ram.rank0.limit')

Tier Capacity on a Rank Output

+-----------------------------------------+
| SYSTEM_PROPERTIES                       |
+-----------------------------------------+
| conf.tier.ram.rank0.limit = 500000000   |
+-----------------------------------------+

To alter the eviction thresholds of the VRAM tier across all ranks, and save the change to the startup configuration:

ALTER TIER Eviction Thresholds Permanently Example

ALTER TIER vram
WITH OPTIONS
(
	'high_watermark' = '95',
	'low_watermark' = '75'
)

To show the change took effect:

SHOW Tier Eviction Thresholds Example

SHOW SYSTEM PROPERTIES
WITH OPTIONS
(
    'properties' =
    '
        conf.tier.vram.default.all_gpus.high_watermark,
        conf.tier.vram.default.all_gpus.low_watermark,
        conf.tier.vram.rank0.all_gpus.high_watermark,
        conf.tier.vram.rank0.all_gpus.low_watermark,
        conf.tier.vram.rank1.all_gpus.high_watermark,
        conf.tier.vram.rank1.all_gpus.low_watermark,
        conf.tier.vram.rank2.all_gpus.high_watermark,
        conf.tier.vram.rank2.all_gpus.low_watermark
    '
)

Tier Eviction Thresholds Output

+-------------------------------------------------------+
| SYSTEM_PROPERTIES                                     |
+-------------------------------------------------------+
| conf.tier.vram.default.all_gpus.high_watermark = 95   |
| conf.tier.vram.default.all_gpus.low_watermark = 75    |
| conf.tier.vram.rank0.all_gpus.high_watermark = 90     |
| conf.tier.vram.rank0.all_gpus.low_watermark = 80      |
| conf.tier.vram.rank1.all_gpus.high_watermark = 95     |
| conf.tier.vram.rank1.all_gpus.low_watermark = 75      |
| conf.tier.vram.rank2.all_gpus.high_watermark = 95     |
| conf.tier.vram.rank2.all_gpus.low_watermark = 75      |
+-------------------------------------------------------+

​Parameters

​Examples

Parameters

Examples