# How to Configure RocksDB Block-Cache (2/4)

+ For the write-intensive scenario:
  + When writing data, the system checks the transaction restriction and reads writecf and lockcf.
  + Because lockcf is usually small, the block-cache size of writecf is more important to the write speed.
+ For the read-intensive scenario:
  + writecf and lockcf are read before defaultcf. You need to balance the block-cache size for writecf and defaultcf. Configure it based on the size of each cf. It is recommended to set the block-cache size for writecf to a larger value.
  + How much hot data exist?
+ [rocksdb.defaultcf]
+ block-cache-size = “20GB”

+ [rocksdb.writecf]
+ block-cache-size = “16GB”

+ [rocksdb.lockcf]
+ block-cache-size = “1GB”
+ Multiple cfs share a block-cache starting from TiKV 3.0.

+ [storage.block-cache]
+ capacity = “30GB”

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