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Re: XFS RAID only writing half the time

To: AndyLiebman@xxxxxxx
Subject: Re: XFS RAID only writing half the time
From: Hendrik Visage <hvisage@xxxxxxxxxxxxxx>
Date: Tue, 25 Nov 2003 17:40:43 +0200
Cc: linux-raid@xxxxxxxxxxxxxxx, linux-xfs@xxxxxxxxxxx
In-reply-to: <1e2.143843bf.2cf4ca4c@xxxxxxx>
References: <1e2.143843bf.2cf4ca4c@xxxxxxx>
Sender: linux-xfs-bounce@xxxxxxxxxxx
User-agent: Mutt/1.4.1i
On Tue, Nov 25, 2003 at 10:07:56AM -0500, AndyLiebman@xxxxxxx wrote:
> A puzzle. 
> I have a P4-3.06 with 1 GB RAM. I have hyperthreading enabled -- and Mandrake 
> 9.2 (2.4.22 kernel) shows that I have 2 CPUs. 

I've seen similar troubles with the SuSE kernels. I believe it has
something to do with some of the desktop/interactive patches that fills
up memory too much before flushing caches.

> Although data is coming into my Linux machine at a rate of 18 MB/sec, I don't 
> see any disk activity for as much as 30 or 40 seconds after I begin recording 
> video. Looking at XOSVIEW, I can see on the memory display that the cache 
> fills up until my memory is almost entirely full, and ONLY THEN does the disk 
> writing activity begin. 
> 
> Usually this is fine, but once in a while -- after capturing video for 20 
> minutes or so, the system will have a "hiccup" and fail to write data fast 
> enough. My video editing application will then stop capturing. I don'

Play with the settings of: 
sysctl -a | grep vm.bdflush
vm.bdflush = 30 500     0       0       500     3000    60      20      0

I've found the right settings would alleviate this hiccup issue.

HEndrik


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