[HDDS-11230] Make RocksDB cache configurable in Ozone Manager

• Type: Improvement
• Status: In Progress
• Priority: Major
• Resolution: Unresolved
• Component/s: OM
• Labels: pull-request-available
• Assignee: weiming
• Reporter: Duong
• Created: 25/Jul/24 01:14
• Updated: 16/Sep/24 14:16

Description

Ozone Manager's performance heavily depends on RocksDB performance. RocksDB cache plays an important role in RocksDB's read performance, especially when a client has to host OM's metadata in not-so-fast hardware. 

Today, OM RocksDB cache is fixed at 256MB (see DBProfile), this is unreasonable because the cache size should depend on the client use-case, i.e. how big is their active key space. For example, if a client always has 1M of hot keys daily, and each key metadata is 1kb, having a cache size of 1GB makes a lot of sense. 

Ref:

• https://github.com/facebook/rocksdb/wiki/Block-Cache
• https://github.com/facebook/rocksdb/wiki/Performance-Benchmarks 

Issue Links

• links to: GitHub Pull Request #7117