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Re: benchmarks

To: linux-xfs@xxxxxxxxxxx
Subject: Re: benchmarks
From: Federico Sevilla III <jijo@xxxxxxxxxxxxxxxxxxxx>
Date: Sat, 14 Jul 2001 03:04:16 +0800
In-reply-to: <200107131550.f6DFogU08171@jen.americas.sgi.com>
References: <XFMail.20010713104223.s-luppescu@uchicago.edu> <200107131550.f6DFogU08171@jen.americas.sgi.com>
Sender: owner-linux-xfs@xxxxxxxxxxx
User-agent: Internet Messaging Program (IMP) 2.3.7-cvs
Quoting Steve Lord <lord@xxxxxxx>:
> An external log is growable, an internal one unfortunately is not, and
> we keep kicking SGI support people who build multi-terabyte filesystems
> without reading the man page.
> 
> Unless you specified otherwise you have two logbufs, all you need to do
> to get the number changed is remount with the new option, so yes, edit
> fstab and reboot.

Does mkfs default to create one or two logbufs? If it default to creating one, 
I presume that it creates an external log which you can then grow using the 
mount option? Is an internal logbuf much better (performance wise) compared to 
an external logbuf (I presume this, but ask anyway).

Maybe we can include this in the FAQ together with the current entry about the 
mount options? Or is the presence in the man page good enough? :)

> If you use O_SYNC anywhere then osyncisdsync as a mount option will
> make xfs O_SYNC behave more like other linux filesystems.

I'm a total ignoramus (;>) when it comes to these nitty-gritties about 
filesystem operation, but in a nutshell maybe we can have information about the 
consequences of this (aside from the already stated speed benefit) on the 
reliability of the data? When is O_SYNC normally called and what does O_DSYNC 
do in comparison with O_SYNC that will make it I/O sync less? :) :)

Thanks a lot for this tweaking help. :)

 --> Jijo

-- 
Federico Sevilla III  :: jijo@xxxxxxxxxxxxxxxxxxxx
Network Administrator :: The Leather Collection, Inc.


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