Re: Streamy FS writes found detrimental.

Daniel Berlin <dan@dberlin.org> writes:

> > Okay, I keep seeing comments like this, and I'm confused as to why
> > they'll help. So I'll have fewer logfile of larger sizes, right?
>
> No.
> The log buffer is what it buffers to *before* writing out the log file.
> If you are doing a ton of logging operations, increasing the log buffer
> will make it hit the disk a lot less.

Okay, so this will assist in speed, but NOT the total size of log
files. So...I'll just run out of disk space faster. Nice. :-)

> > The total sum of log operations written is going to be the same
> > regardless, right?
>
> Yes, but it's *when* it writes them that matters.
> If it has to flush because the log buffer is full, everything waits.
> If it's doing it while committing a transaction, it's writing to the
> disk anyway, so it's nowhere near as costly.

No, it's not *when* we write them that matters. I did not fill up
1.74 gigs of disk space because my log files were written today vs.
being written tomorrow. I filled up 1.74 gigs of disk because they
were written at all.

Where are we miscommunicating here? I think we're both aiming to
solve some problems, just not the same ones.

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Received on Sat Oct 21 14:37:10 2006