> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kinetica.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ALTER TIER

<a id="sql-tier-alter" />

The size & eviction thresholds of
[storage tiers](/content/rm/concepts#rm-concepts-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](/content/sql/system_properties/show-system-properties#sql-show-system-properties).

```sql title="ALTER TIER Syntax" theme={null}
ALTER TIER <tier name>
WITH OPTIONS (<tier property name> = <tier property value>[,...])
```

## Parameters

<AccordionGroup>
  <Accordion title="<tier name>" id="<tier-name>" defaultOpen>
    Name of the [storage tier](/content/rm/concepts#rm-concepts-tiers) to alter.

    <div>
      <table class="table w-full [&_td]:min-w-[150px] [&_th]:text-left [&_td[data-numeric]]:tabular-nums">
        <thead>
          <tr>
            <th>Name</th>
            <th>Description</th>
          </tr>
        </thead>

        <tbody>
          <tr>
            <td><code>VRAM</code></td>
            <td>Alter the [VRAM tier](/content/rm/concepts#rm-concepts-tiers-vram).</td>
          </tr>

          <tr>
            <td><code>RAM</code></td>
            <td>Alter the [RAM tier](/content/rm/concepts#rm-concepts-tiers-ram).</td>
          </tr>

          <tr>
            <td><code>DISK\[n]</code></td>
            <td>Alter the specified [disk tier](/content/rm/concepts#rm-concepts-tiers-disk).</td>
          </tr>

          <tr>
            <td><code>PERSIST</code></td>
            <td>Alter the [persist tier](/content/rm/concepts#rm-concepts-tiers-persist).</td>
          </tr>

          <tr>
            <td><code>COLD\[n]</code></td>
            <td>Alter the specified [cold storage tier](/content/rm/concepts#rm-concepts-tiers-cold).</td>
          </tr>
        </tbody>
      </table>
    </div>
  </Accordion>

  <Accordion title="WITH OPTIONS" id="with-options" defaultOpen>
    Optional indicator that a comma-delimited list of `tier property name` /
    `tier property value` assignments will follow.

    <div>
      <table class="table w-full [&_td]:min-w-[150px] [&_th]:text-left [&_td[data-numeric]]:tabular-nums">
        <thead>
          <tr>
            <th>Property</th>
            <th>Description</th>
          </tr>
        </thead>

        <tbody>
          <tr>
            <td><code>capacity</code></td>
            <td>Size, in bytes, of a rank in this tier; for *RAM*, *disk*, & *persist* tiers.</td>
          </tr>

          <tr>
            <td><code>high\_watermark</code></td>
            <td>High watermark [eviction](/content/rm/concepts#rm-concepts-wb-eviction) threshold for a rank in this tier; for *VRAM*, *RAM*, *disk*, & *persist* tiers.</td>
          </tr>

          <tr>
            <td><code>low\_watermark</code></td>
            <td>Low watermark [eviction](/content/rm/concepts#rm-concepts-wb-eviction) threshold for a rank in this tier; for *VRAM*, *RAM*, *disk*, & *persist* tiers.</td>
          </tr>

          <tr>
            <td><code>wait\_timeout</code></td>
            <td>Timeout, in seconds, for reading from or writing to this tier; for *cold storage* tiers.</td>
          </tr>

          <tr>
            <td><code>persist</code></td>
            <td>Whether to save this change to the database configuration so that it will stay in effect after a database restart; default is <code>true</code>.</td>
          </tr>

          <tr>
            <td><code>rank</code></td>
            <td>Specific rank in this tier to apply the change to; default is to apply the change to all ranks in the tier.</td>
          </tr>
        </tbody>
      </table>
    </div>
  </Accordion>
</AccordionGroup>

<a id="sql-tier-alter-ex" />

## Examples

To alter the capacity of the [RAM tier](/content/rm/concepts#rm-concepts-tiers-ram) on rank 0 to *500MB*
temporarily (until the database is restarted):

```sql ALTER TIER Capacity on a Rank Temporarily Example theme={null}
ALTER TIER ram
WITH OPTIONS
(
	'capacity' = '500000000',
	'rank' = 0,
	'persist' = false
)
```

To show the change took effect:

```sql SHOW Tier Capacity on a Rank Example theme={null}
SHOW SYSTEM PROPERTIES
WITH OPTIONS ('properties' = 'conf.tier.ram.rank0.limit')
```

```SHOW Tier Capacity on a Rank Output theme={null}
+-----------------------------------------+
| SYSTEM_PROPERTIES                       |
+-----------------------------------------+
| conf.tier.ram.rank0.limit = 500000000   |
+-----------------------------------------+
```

To alter the eviction thresholds of the [VRAM tier](/content/rm/concepts#rm-concepts-tiers-vram) across all ranks, and
save the change to the startup configuration:

```sql ALTER TIER Eviction Thresholds Permanently Example theme={null}
ALTER TIER vram
WITH OPTIONS
(
	'high_watermark' = '95',
	'low_watermark' = '75'
)
```

To show the change took effect:

```sql SHOW Tier Eviction Thresholds Example theme={null}
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
    '
)
```

```SHOW Tier Eviction Thresholds Output theme={null}
+-------------------------------------------------------+
| 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      |
+-------------------------------------------------------+
```


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