From owner-freebsd-stable  Mon Mar 12 15:10:20 2001
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References: <200103122036.VAA99695@freebsd.dk>
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From: "J.Goodleaf" <john@goodleaf.net>
To: stable@FreeBSD.ORG
Subject: Re: Disk I/O problem in 4.3-BETA
Date: Mon, 12 Mar 2001 23:20:46 GMT
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I don't adequately understand the difference between what you're talking 
about here and what softupdates does. I have used softupdates for some time, 
but now I'm nervous! Can you point me toward the nearest info source, that I 
might RTFM and refrain from bugging you guys? (Given that I already tried 
man softupdates and man tunefs doesn't tell me anything.)
 -J 

Alfred Perlstein writes: 

> * Kevin Oberman <oberman@es.net> [010312 13:46] wrote:
>> Soren, 
>> 
>> Thanks for the quick reply! And right on the button, too. 
>> 
>> I have turned the write cache back on (any relevance to "write cache"
>> being abbreviated to "WC"? :-) and the time to dd the slices went back
>> to 10 and 5 minutes (actually 489 and 287 seconds). 
>> 
>> How serious is the possible corruption issue, anyway. The loss in
>> performance is pretty drastic although it may be that dd is an
>> especially bad case, but I really don't like to corrupt my disks,
>> either.
> 
> If basically running with blind write caching turned on is akin to
> running your filesystem in async mode.  This is because write
> caching gives the drive license to lie about completing a write,
> the various ordering of writes are effectively bypassed.  If you
> crash without these dependancies actually written to the disk, when
> you come back up you have a good chance of losing large portions
> of your filesystem. 
> 
> -- 
> -Alfred Perlstein - [bright@wintelcom.net|alfred@freebsd.org]
> Daemon News Magazine in your snail-mail! http://magazine.daemonnews.org/ 
> 
> 
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