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Date:      Tue, 28 Sep 2010 14:52:54 +0200
From:      Ivan Voras <ivoras@freebsd.org>
To:        freebsd-performance@freebsd.org
Subject:   Re: gstripe small transaction size
Message-ID:  <i7soet$o9c$1@dough.gmane.org>
In-Reply-To: <4CA1E33C.70200@softhammer.net>
References:  <4CA14009.4050906@softhammer.net> <i7sguk$gi2$1@dough.gmane.org> <4CA1E33C.70200@softhammer.net>

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On 09/28/10 14:44, Stephen Sanders wrote:
> Increasing MAXPHYS and turning up the stripe size won't have the effect
> I'm looking for ?

I've missed you tuned MAXPHYS up. Yes, in this case it should work, if 
the underlying driver supports larger IO sizes.

As I see it, if all of these are true:
	* MAXPHYS is upped to be at least stripe_size * number_of_drives (and 
possibly 2x that, to use "fast mode" of gstripe)
	* vfs.hirunningspace is > MAXPHYS
	* the driver supports IOs of at least your stripe_size
	* the file system doesn't introduce unnecessary choppiness in IO (i.e. 
use soft-updates)

it is reasonable to expect streaming IO to your array will use larger 
transactions.





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