fsync and speed

Joe Geiser jgeiser at csillc.com
Mon Jul 27 02:14:38 GMT 1998


> Recently some people have been asking about the speed of copying large
> files. In my experience the main cause of _really_ bad throughput is
> the common that many Windows application programmers don't know the
> difference between sync and flush.


> So, shall we add an option "no sync = yes/no" to go aong with our
> current "always sync = yes/no" ? Those fsync calls are generated
> because the stupid client programmer decided to call sync on every
> write to the file. He probably wanted flush but didn't understand the
> difference. sync is _very_ expensive whereas flush is cheap. sync is
> pointless unless you are writing a transaction system. sync only ever
> makes a difference if the server crashes (ie. the OS crashes, not just
> the process).

Being relatively new to this list, but being deep into the Windows OS (but
not inside MS), I can confirm, just as you have, this irritating problem.

I would agree with your proposal of adding this option to smb.conf and would
welcome it.  Because I use Samba (under MPE/iX and am not finishing off the
18p8 port) for backup purposes, I run into this all of the time.

Make my vote "yes".

Best Regards,

Joe Geiser
CSI Business Solutions, LLC
Phone: +1 (215) 945.8100  Fax: +1 (215) 943.8408
Toll-Free (US/Canada): (800) 498-4802

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