DM-WRITEBOOST

Log-structured Caching for Linux

Overview

dm-writeboost is an implementation of Disk Caching Disk(DCD).
DCD is an extra logical block layer that gathers in-coming small random writes into a big sequential write which then performs high throughput and low latency. See also the DCD paper [1].

Features

• Log-structured caching principle ensures the durability to server crash.
• Unlike bcache, dm-writeboost is a complete loadable kernel module.
• Fully supports REQ_FLUSH/REQ_FUA operations to emulate block device.
• Kernel versions since 3.2 are widely supported.
• Capable of performing 375kiops(1.5GB/sec) random writes with a fast enough cache.
• Concurrency not discussed in DCD paper is implemented.
• Auxiliary daemon autonomously controls the behavior of the kernel module.

References

• [1] Y. Hu and Q. Yang -- DCD Disk Caching Disk: A New Approach for Boosting I/O Performance (1995)

Quick Start

You are provided with nice scripts for quick starting.
Assuming you have expanded dm-writeboost under /home/akira,

(1) [common] Configure device paths for backing store and cache device.

$ cd /home/akira/dm-writeboost  
$ vi config

(2) If the kernel doesn't have dm-writeboost merged, please build the module first.

$ source build

(3) [common] Load dm-writeboost into the kernel.
How to Load dm-writeboost module depends on your environment.

If you are using kernel with dm-writeboost merged,

# modprobe dm-writeboost

If you will use the portable module in this repo,

# cd Driver
# insmod dm-writeboost.ko

(4) [common] Run prepare script

# source prepare  

and you are now ready for /dev/mapper/perflv powered by dm-writeboost.
Try testing and performance and see what is happening.

Contributing to dm-writeboost

Any type of contribution is all welcome.
Not even by code, by documents or by issue reporting is granted as a form of contribution.

To contribute by code or documents, pull-requests style seems to be a nice idea.
To make pull-requests,

1. Fork it.
2. Create your feature branch (git checkout -b my-new-feature).
3. Commit your changes (git commit -am 'Added some features').
4. Push to the forked repository (git push origin my-new-feature).
5. Create a new Pull Request.

Developer Info

Akira Hayakawa (@akiradeveloper)
e-mail: [email protected]