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Date:      Wed, 12 Dec 2012 09:43:10 +1100
From:      Peter Jeremy <peter@rulingia.com>
To:        Dieter BSD <dieterbsd@engineer.com>
Cc:        freebsd-hackers@freebsd.org
Subject:   Re: FreeBSD for serious performance?
Message-ID:  <20121211224310.GB35245@server.rulingia.com>
In-Reply-To: <20121211204323.310760@gmx.com>
References:  <20121211204323.310760@gmx.com>

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On 2012-Dec-11 15:43:21 -0500, Dieter BSD <dieterbsd@engineer.com> wrote:
>I care about data integrity, so things like ECC are on my must-have list.

Well, that's supported by all server CPUs (AMD Opteron, Intel Itanium,
Intel Xeon, Oracle/Sun SPARC) and some desktop CPUs (most AMD x86 chips).

>A high clock rate doesn't help when some device driver does
>
>block_all_interrupts();
>while(1)
> DELAY(MIGHT_AS_WELL_BE_FOREVER);
>
>At least four device drivers have caused me to lose data this way.

Which device drivers?  We can't fix problems we don't know about.

>Data integrity, and yes, reliability, that sort of thing.

Virtually everything except some embedded and consumer-grade x86
systems manage that.

>But without NCQ I'm only getting ~6% of what I should be getting.

So, in one sentence you state that ECC is a "must have" and then you
complain that that FreeBSD doesn't support NCQ on an old, low-end
(consumer-grade) chipset that doesn't support ECC.

>It's not some rare, obscure chip. Lots of boxes have it.

None that support ECC, so you wouldn't be interested in any of them.

>>> I never found a way to boot from different partitions, much less
>>> different disks with GPT.

Yes, this is a limitation of FreeBSD's GPT loader.  So far, no-one has
written the code to support multiple boot partitions or disks.  Note
that most BIOS's allow you to select the boot disk - which is a
workaround.

--=20
Peter Jeremy

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