# Adjust Block-Cache Parameter Configuration

+ Online adjustment (experimental function)
+ Confirm if the adjustment is in effect

```
set config tikv storage.block-cache.capacity='8155MB';
Query OK, 0 rows affected (0.02 sec)

show config where name ='storage.block-cache.capacity';
+------+-----------------------+----------------------------------------+-------------+
| Type | Instance              | Name                                   | Value       |
+------+-----------------------+----------------------------------------+-------------+
| tikv | 172.x.x.x:20181       | storage.block-cache.capacity           | 8155MiB     |
+------+-----------------------+----------------------------------------+-------------+
1 row in set (0.01 sec)
```
------------------------------------------------------------
If it is confirmed that the OOM is due to improper block-cache settings, it can be mitigated by adjusting the corresponding parameters.
Starting with v4.0, online configuration of cluster parameters is supported. This change is mainly to use SQL to update some configuration parameters of various components, including TiDB, TiKV, and PD online. We can tune the performance of individual components through online configuration changes without restart the cluster components. To adjust the block-cache configuration online, use the following method:
set config tikv storage.block-cache.capacity='8155Mb';
Query OK, 0 rows affected (0.02 sec)

After the adjustment is complete, confirm that the adjustment takes effect:
```
show config where name ='storage.block-cache.capacity';
+------+--------------------+------------------------------+---------+
| Type | Instance | Name | Value |
+------+--------------------+------------------------------+---------+
| tikv | 172.x.x.x:20181 | storage.block-cache.capacity | 8155MiB |
+------+--------------------+------------------------------+---------+
1 row in set (0.01 sec)
```