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Date: Fri, 09 Apr 2010 15:14:38 +0300
From: Andriy Gapon <avg@icyb.net.ua>
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To: Alexey Tarasov <me@lexasoft.ru>
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Cc: freebsd-current@freebsd.org
Subject: Re: ZFS raidz and 4k sector disks
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on 09/04/2010 14:14 Alexey Tarasov said the following:
> Hello.
> 
> I see considerably increased performance when creating over gnop -S 4096 virtual disk. Even when I create zpool over raw disks the performance is very bad and concurent writes stalls. When using gnop, zfs works VERY fast!
> 
> Btw, here is another discussion, may be there is a bug in a mav@ commit, because he has added support for >512 sector size:
> http://lists.freebsd.org/pipermail/freebsd-current/2010-April/016495.html


Looks like I was wrong:
        /*
         * Determine the device's minimum transfer size.
         */
        *ashift = highbit(MAX(pp->sectorsize, SPA_MINBLOCKSIZE)) - 1;

This is in vdev_geom_open and SPA_MINBLOCKSIZE is 512.

-- 
Andriy Gapon