# Review Block-Cache Parameter Configuration

+ Grafana monitoring (TikV-Details —> RocksDB KV —> Block cache size)


![right](./student-guide/diagram/24-block-cache-parameter-configuration-01-01.png)

+ Check the parameter configuration storage.block-cache.capacity (45% to 60%)

```
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)
```
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BlockCache uses LRU algorithm to eliminate low-frequency access data. By default, TiKV uses 45% of the total system memory size for BlockCache. We can also modify the storage.block-cache.capacity parameter to a suitable value, but it is not recommended to exceed 60% of the total system memory. The remaining memory space needs to be reserved for page cache, etc. Also, in the case of a single-instance multi-instance TiKV deployment, you need to pay more attention to the configuration of this value.

Therefore, if the TiKV server is experiencing OOM, check whether the block-cache value in the cluster environment is reasonable by the following method:

- Grafana monitoring: TikV-Details —> RocksDB KV —> Block cache size