On Tue, 2002-02-26 at 15:31, cmpilato@collab.net wrote:
> 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.
Correct.
I thought you were complaining of the performance of streamy fs writes.
If you are complaining about log file size, that's easy to remedy.
BTW guys, I looked at libxdfs (xdelta's bdb based FS library), and it
does what i was doing (log file removal in a thread).
Hey guys, are we replacing items when we don't need to? (IE rewriting
data with the same data) If so, this will greatly increase the log file
size, since replaces are logged and include both the original, and
replacement, data.
I get the feeling we rewrite stuff for no reason at times, given the log
file sizes.
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Received on Sat Oct 21 14:37:10 2006