Search Postgresql Archives

Re: [ADMIN] Running with fsync=off

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Martijn van Oosterhout <kleptog@xxxxxxxxx> writes:
> On Wed, Dec 21, 2005 at 11:30:15PM -0800, Benjamin Arai wrote:
>> Somebody said running "sync ; sync; sync" from the console.  This seems

> The reason is partly historical. On some OSes running sync only starts
> the process but returns immediatly. However, there can only be one sync
> at a time so the second sync waits for the first the finish. The third
> is just for show. However, on Linux at least the one sync is enough.

No, the second and third are both a waste of time.  sync tells the
kernel to flush any dirty buffers to disk, but doesn't wait for it to
happen.

There is a story that the advice to type sync twice was originally given
to operators of an early Unix system, as a quick-and-dirty way of making
sure that they didn't power the machine down before the sync completed.
I don't know if it's true or not, but certainly the value would only
appear if you type sync<RETURN>sync<RETURN> so that the first sync is
actually issued before you type the next one.  Typing them all on one
line as depicted is just a waste of finger motion.

			regards, tom lane


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]
  Powered by Linux