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Re: Sharded FSFS repositories - summary

From: Justin Erenkrantz <justin_at_erenkrantz.com>
Date: 2007-03-17 16:15:29 CET

On 3/17/07, John Szakmeister <john@szakmeister.net> wrote:
> If we're going to make this configurable, with a reasonable default, can
> we default with something that's more reasonable for typical and mobile
> users? And for those who are clearly out of the norm, such as Apache,
> they can specify something more suitable to their environment?

I would be *very* cautious about having any customizability at all for
a few reasons:

1) What consequences would there be if the user changes it after the
repos goes live? All of a sudden their repos could be corrupt: FSFS
would think their repos is empty when it may have been under a new
sharding scheme. Ouch.

2) What performance penalty are we going to add by introducing a new
file? This is yet another file that needs to be open'd, read'd, and
close'd. IIRC, there is no config file for FSFS right now - so this
would mandate the introduction of a new one. Needless to say, on a
high-traffic site, this is going to introduce unnecessary I/O
overhead. (Yes, the OS's cache may minimize this, but there's still a
non-zero cost.)

So, I'd rather we just hard-code a setting that works: if an admin
wants to change the #define, they can - but they have to dork with the
source to do so. -- justin

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Received on Sat Mar 17 16:15:45 2007

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