libeatmydata

libeatmydata is a small LD_PRELOAD library designed to (transparently) disable fsync (and friends, like open(O_SYNC)). This has two side-effects: making software that writes data safely to disk a lot quicker and making this software no longer crash safe.

DO NOT use libeatmydata on software where you care about what it stores. It's called libEAT-MY-DATA for a reason.

Source

I've recently been migrating things over to git from the old BZR repository.

Git repositories are on launchpad and github

Grab the latest by just doing git clone https://github.com/stewartsmith/libeatmydata.git - although most Linux distros package libeatmydata as eatmydata

Download: The launchpad download page has all the latest libeatmydata downloads.

You can also download the source tarball from here: libeatmydata-105.tar.gz and GPG signature: libeatmydata-105.tar.gz.asc.

Install

If installing from source, do the following:

git clone https://github.com/stewartsmith/libeatmydata.git (or extract from source tarball) cd libeatmydata autoreconf -i (if building from git only) ./configure make make check sudo make install

Using

Once libeatmydata is installed (either from a package or from source like above, simply run the eatmydata wrapper script:

eatmydata foo

Platform Support

I use it primarily on Linux. Others have reported success on MacOS X, OpenSolaris, Solaris, Debian GNU/kFreeBSD. Patches welcome!

Contributing

You can email me directly with patches. Development is hosted on launchpad and has been transitioning to github.

Performance Improvements

Running mysql-test-run --do-test=innodb without/with libeatmydata:

TEST RESULT TIME (ms) TIME (with libeatmydata) ---------------------------------------------------------------------------------- main.innodb-lock [ pass ] 4523 4323 main.innodb-replace [ pass ] 102 56 main.innodb-ucs2 [ pass ] 5786 1084 main.innodb [ pass ] 78306 24900 main.innodb_gis [ pass ] 2647 1544 main.innodb_mysql [ pass ] 86810 68579 main.innodb_notembedded [ pass ] 198 150 main.innodb_timeout_rollback [ pass ] 2990 2750 main.innodb_trx_weight [ pass ] 1608 841 --------------------------------------------------------------- Stopping All Servers All 9 tests were successful. The servers were restarted 7 times WITHOUT: Spent 182.97 seconds actually executing testcases WITH : Spent 104.227 seconds actually executing testcases WITHOUT: WITH: real 3m36.053s real 2m10.610s user 0m42.323s user 0m41.939s sys 0m2.844s sys 0m2.356s

This saves us about a third of the total runtime!

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Stewart Smith (stewart@flamingspork.com)