dm-writeboost

Log-structured Caching for Linux

Overview

dm-writeboost is originated from Disk Caching Disk (DCD). DCD, implemented in Solaris, is an OS-level IO controller that builds logs from in-coming writes (data and metadata) and then writes the logs sequentially similar to log-structured filesystem. dm-writeboost implements the concept on Linux's device-mapper in more sophisticated way. As a further extension, dm-writeboost supports read-caching which also writes data sequentially.

Documents

• dm-writeboost-quickstart
• doc/dm-writeboost-readme.txt
• dm-writeboost-internal
• Wiki

Features

• Durable: Any power failure can't break consistency because each log consists of data, metadata and the checksum of the log itself.
• Lifetime: Other caching software (e.g. dm-cache) separates data and metadata and therefore submits writes to SSD too frequently. dm-writeboost, on the other hand, submits only one writes for hundreds of data and metadata updates so the SSD lives longer since SSD's lifetime depends on how many writes are submitted.
• Fast: Since the sequential write is the best I/O pattern for every SSD and the code base is optimized for in-coming random writes, the write performance is the best among all caching drivers including dm-cache and bcache.
• Portable: All kernel version 3.10 or later is supported with minimum compile-time macros.

Usage

• Install: sudo make install to install and sudo make uninstall to uninstall. sudo make uninstall MODULE_VERSION=xxx can uninstall specific version that's installed. DKMS is required so please install it beforehand. (usually available in package system)
• Make a device: Make a script to build a caching device. Please read doc/dm-writeboost-readme.txt for the dmsetup command detail. After reboot, you need to rebuild the caching device rather than reformatting as in the initial setup.

Distribution Packages

• Debian
• Ubuntu

Related Projects

• https://github.com/akiradeveloper/dm-writeboost-tools: Tools to help users analyze the state of the cache device
• https://gitlab.com/onlyjob/writeboost: A management tool including init script
• https://github.com/akiradeveloper/device-mapper-tests: Testing framework written in Rust

Related works

• Y. Hu and Q. Yang -- DCD Disk Caching Disk: A New Approach for Boosting I/O Performance (1995) (http://www.ele.uri.edu/research/hpcl/DCD/DCD.html)
• G. Soundararajan et. al. -- Extending SSD Lifetimes with Disk-Based Write Caches (2010) (https://www.usenix.org/conference/fast-10/extending-ssd-lifetimes-disk-based-write-caches)
• Y. Oh -- SSD RAID as Cache (SRC) with Log-structured Approach for Performance and Reliability (2014) (https://ysoh.files.wordpress.com/2009/05/dm-src-ibm.pdf)

Award

Awarded by Japanese OSS Encouragement Award. Thanks!

License

Copyright (C) 2012-2024 Akira Hayakawa <ruby.wktk@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

Developer Info

Akira Hayakawa (@akiradeveloper)
e-mail: ruby.wktk@gmail.com