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Date:      Fri, 15 Oct 2004 14:16:11 -0400
From:      Kenneth Culver <culverk@sweetdreamsracing.biz>
To:        fandino@ng.fadesa.es
Cc:        freebsd-questions@freebsd.org
Subject:   Re: FreeBSD and poor ata performance
Message-ID:  <20041015141611.t8cgso00co4wggoc@www.sweetdreamsracing.biz>
In-Reply-To: <41700BBB.50003@ng.fadesa.es>
References:  <416EB6B1.6060405@ng.fadesa.es> <416F849F.8020508@solid-state-logic.com> <416F90E6.10108@ng.fadesa.es> <200410151223.33355.howells@kde.org> <416FF477.4010408@ng.fadesa.es> <20041015131432.srwo0wog000skgcs@www.sweetdreamsracing.biz> <41700BBB.50003@ng.fadesa.es>

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Quoting fandino <fandino@ng.fadesa.es>:

> Kenneth Culver wrote:
>>> well, my usage pattern is write a big file and few seconds later 
>>> read it. So my tests
>>> were valid for the use of the computer.
>>>
>>> But you have reason, I must provide a more formal report. I redid all test
>>> with bonnie++ and results shows Linux (56848 K/sec) two times faster than
>>> FreeBSD (26347 K/sec)
>>>
>>> Any help will be appreciated!
>>>
>>>
>>> Linux test  (slackware 8.1, kernel 2.4.18, ext2 filesystem):
>>
>>
>> This test isn't really a fair test either. The ext2 filesystem uses 
>> async io,
>> and doesn't do any kind of journaling to ensure data integrity in 
>> the event of
>> a crash. FreeBSD isn't using async, it uses softupdates. Because of this
>> FreeBSD SHOULD be slower... but it'll be a lot more reliable than 
>> linux in the
>> event of a power outage for example. The ext2 filesystem is extremely
>> unreliable, and will almost always lose data when there's a crash or power
>> outage.
>
> but then why does read/write tests over raw devices performs so bad?
> AFAIK on raw devices not filesystem, journaling, caches, etc are involved.
> _______________________________________________

Like I said before, you might not have been testing the throughput of 
the disks,
instead you may have been testing the throughput of /dev/zero.

Ken



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