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Re: FSFS nosync

From: Peter Samuelson <peter_at_p12n.org>
Date: Thu, 15 Dec 2011 16:04:13 -0600

[Philip Martin]
> If we had such a flag in fsfs.conf (Stefan suggests
> "eat-my-data=yes") the code could write all the same data in the same
> order but avoid making any flush calls thus allowing the OS to order
> physical writes for optimum speed.

Given the main use case is a distinct svnadmin operation, we could just
recommend the 'eatmydata' binary (I'm guessing this is what Stefan was
thinking of when he suggested that option name) which uses an ELF
preload trick to transparently disable syscalls like fsync() and
fdatasync().

    http://packages.debian.org/sid/eatmydata
    https://launchpad.net/libeatmydata

It apparently works on Linux and Solaris. Don't know if that's enough
coverage for general interest. Anyway, on Debian at least, you can
then run

    eatmydata svnadmin load -q /tmp/dumpfile ...

Given this more general solution that IMO sysadmins should have in
their toolbox anyway, I'm +1 on publicising it a bit more, and -0 on
reimplementing it in svnadmin/libsvn_repos/libsvn_fs.

Peter
Received on 2011-12-15 23:04:57 CET

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