This is the implementation of the paper "GearDB: A GC-free Key-Value Store on HM-SMR Drives with Gear Compaction" appeared in FAST 2019.
We implement GearDB based on LevelDB.
To access HM-SMR drives, GearDB uses the Libzbc library which provides functions to manipulate disks supporting ZBC and ZAC commands. To run GearDB, please download and install Libzbc first:
> git clone https://github.com/hgst/libzbc
> sh ./autogen.sh
> ./configure
> make
> make install //necessary
- If you use an HM-SMR drive (Host-managed shingled magnetic recording drive) as your storage medium, **skip this step. **If you do not have one, emulate an HM-SMR drive with your conventional HDD as following :
> cd libzbc
> zbc_set_zones /dev/sdb1 set_sz 256 256 //Block device /dev/sdb1 is an example
- Add the path of your HM-SMR drive or emulated HM-SMR drive (e.g., /dev/sdb1) in file "/GearDB/hm/hm_status.h":
static const char smr_filename[]="/dev/sdb1";
- We have modified the Makefile to make the compilation of GearDB same with LevelDB.
> make -j4
- Now you may run and test GearDB with out-static/db_bench. The "out-static/libleveldb.a." is still available in GearDB.
> ./out-static/db_bench
3 GearDB's differences with LevelDB
To get the source code of LevelDB in the same edition used by GearDB, do the following steps:
> git clone https://github.com/google/leveldb
> cd leveldb
> git checkout 23162ca1c6d891a9c5fe0e0fab1193cd54ed1b4f
Or, you may download it at : https://github.com/google/leveldb/tree/23162ca1c6d891a9c5fe0e0fab1193cd54ed1b4f
Since GearDB is implemented based on LevelDB, here we list the main differences between GearDB and LevelDB.
- Added file: hm/*。
- Modified file:
db/builder.cc
db/builder.h
db/db_bench.cc
db/db_impl.cc
db/db_impl.h
db/leveldbutil.cc
db/table_cache.cc
db/table_cache.h
db/version_set.cc
db/version_set.h
include/leveldb/db.h
include/leveldb/env.h
util/env_posix.cc
util/options.cc
build_detect_platform
Makefile
We used them to complete our implementation.
This version does not support reloading databases, which means it will get an error if you open the database again after the program finished. The version supported reloading is implemented. However, it makes the operation of GearDB a little bit cumbersome. If you test GearDB with the macro-benchmark YCSB, the reload function will be needed. You may contact 993096281@qq.com to get the support for reloading a database.
- Ting Yao (tingyao@hust.edu.cn )
- Zhiwen Liu (993096281@qq.com)
- Yiwen Zhang (zhangyiwen@hust.edu.cn)