Eatmydata

4 weeks ago 1

An LD_PRELOAD library that disables all forms of writing data safely to disk. fsync() becomes a NO-OP, O_SYNC is removed etc.

The idea is to use in testing to get faster test runs where real durability is not required.

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

see http://www.flamingspork.com/projects/libeatmydata

Debian/Ubuntu and friends:

To build from source, you will need autoconf, autoconf-archive, automake, libtool, and a compiler (say, gcc).

Then, build and install like so:

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

When running part of the MySQL test suite in 2007 on my laptop:

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

libeatmydata was the product of a talk I gave back at linux.conf.au 2007, titled "Eat My Data: How Everybody gets File IO Wrong" - I also gave this talk at OSCON. This talk went over the common mistakes people make when using POSIX file IO routines.

You can watch a video recording of this talk at:

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