README.md

RocksDB utilizing Tiered Storage and Hybrid Compression

This work is a scheme utilizing RocksDB, allowing users to store each of the levels of RocksDB into heterogeneous storage media and decide which compression technique they want to use on those levels.

Download

git clone --recurse-submodules  https://github.com/DKU-StarLab/TieredStorageHybridComp.git

Dependencies

• Tiered Storage: This scheme can be used with the storage devices on the user machine with no customizations since the changes we made are limited to the application level.
• Hybrid Compression: The following compression libraries should be linked. In case they aren't, they cannot be used in setting up the hybrid compression within levels and no compression will be used by default.
  • Snappy: https://google.github.io/snappy/
  • LZ4: https://github.com/lz4/lz4
  • Zstd: https://facebook.github.io/zstd/
  • zlib: http://www.zlib.net/

Compilation

Compile the code with the same options as compiling RocksDB: 
https://github.com/facebook/rocksdb/blob/main/INSTALL.md

Benchmarking

• Setting up tiered storage
  1. Create directories to hold the levels of the LSM-tree in their corresponding storage device.
  2. Using the db_bench tool, specify the flags needed for tiered storage.
• Run benchmark with db_bench using the flags for tiered storage along with other db_bench options
  • use_tiered_storage - [default:0] [Possible values: 0 or 1] Boolean value which tells the LSM-tree if tiered storage will be used or not.
  • tiered_storage_path - [default:empty] [Possible values: STRING] String value of the comma-separated storage paths.

Example:
Storage paths:
- /mnt/ssdoptane
- /mnt/ssdnvme
- /mnt/ssdsata
- /mnt/hdd

Run db_bench with flags use_tiered_storage and tiered_storage_path
./db_bench --benchmarks=fillrandom --use_tiered_storage=1 --tiered_storage_path=/mnt/ssdoptane,/mnt/ssdnvme,/mnt/ssdsata

This benchmark will store L0 in "/mnt/ssdoptane", L1 in "/mnt/ssdnvme", L2 in "/mnt/ssdsata", and the rest of the levels (L3 onwards) in "/mnt/hdd"

• Utilizing hybrid compression
  • Run benchmark with db_bench using the flags for hybrid compression along with other db_bench options
    • use_hybrid_compression - [default:0] [Possible values: 0 or 1] Boolean value which tells RocksDB if hybrid compression will be used or not.
    • hybrid_compression_type - [default:empty] [Possible values: STRING] Comma-separated names of supported compression techniques. Note that if the compression technique is not supported, it will default to not using any compression for the specified level.

Example:
Run db_bench with flags use_hybrid_compression and hybrid_compression_type
./db_bench --benchmarks=fillrandom --use_hybrid_compression=1 --hybrid_compression_type=none,snappy,lz4,zstd

This benchmark will use no compression in L0, Snappy in L1, LZ4 in L2, and Zstd for the rest of the levels.