Subject: Re: Bad performance, biowait on raid device
To: None <>
From: None <>
List: tech-kern
Date: 03/14/2006 18:23:43
On Tue, Mar 14, 2006 at 06:09:51PM +0100, Stefan Wurstbauer wrote:
> I'm running NetBSD 3.0 on a Dell PowerEdge 4600 server. The disks are
> 4 scsi disks / raid 5 on a hardware raid controller, mounted as a ffs
> filesystem (without softdeps). 

Without softdeps, the filesystem is operating in synchronised mode,
meaning that almost all operations are serialised. Compare that with
softdep or async mounts, where most operations are done in parallel and
send as batch to the controller.