[ZODB-Dev] Use of fsync in FileStorage
Shane Hathaway
shane at hathawaymix.org
Fri Jul 30 00:34:06 EDT 2004
On Thursday 29 July 2004 13:51 pm, Christian Robottom Reis wrote:
> Doesn't really seem to make *that* much of a difference; this may have
> to do with VFS fsync behaviour when using raid-1, or perhaps the write
> behaviour on these specific hard drives -- I am surprised so many others
> saw so much fluctuation in times.
I would expect fsync to make a big difference. fsync waits for the disk to
write everything currently pending to disk. Disks without a battery backup
have to seek in order to sync reliably, and since seek time is a few
milliseconds, it's easy to see why a box would be limited to 100-200 fsyncs
per second, regardless of the processor speed.
I don't like the way Zope behaves with respect to the disk. It churns the
disk before responding to the browser; no other program I use is so paranoid.
Why bother? When I actually care about the data Zope is storing, I use a
UPS. Does fsync provide any benefit that a UPS doesn't?
Shane
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