Date: Sat, 28 Aug 2010 13:05:49 -0300 From: Thiago Damas <tdamas@gmail.com> To: Ilya Bakulin <webmaster@kibab.com> Cc: =?ISO-8859-1?Q?Dag=2DErling_Sm=F8rgrav?= <des@des.no>, hackers@freebsd.org, geom@freebsd.org Subject: Re: Support for WD Advanced Format disks Message-ID: <AANLkTikwgiw7r1KFdMVYaoomMGmvpjw=2rGtqM%2BZ3at2@mail.gmail.com> In-Reply-To: <20100828195024.3d671a76@kibab.com> References: <86wrry1hwv.fsf@ds4.des.no> <20100828130912.48205a47@kibab.com> <20100828195024.3d671a76@kibab.com>
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You read: "ATA 4K sector issues" http://lists.freebsd.org/pipermail/freebsd-hackers/2010-March/031154.html 2010/8/28 Ilya Bakulin <webmaster@kibab.com>: > On Sat, 28 Aug 2010 13:09:12 +0400 > Ilya Bakulin <webmaster@kibab.com> wrote: > >> Right now I'm running phybs -w /dev/ad7p1 > > Well, phybs finished. > Results: > kibab-desktop# ./phybs -w /dev/ad7p1 > count size offset step msec tps kBps > > 131072 1024 0 4096 3098125 0 42 > 131072 1024 512 4096 3100047 0 42 > > 65536 2048 0 8192 1505809 0 87 > 65536 2048 512 8192 1505179 0 87 > 65536 2048 1024 8192 1506127 0 87 > > 32768 4096 0 16384 1522343 1 86 > 32768 4096 512 16384 1521017 1 86 > 32768 4096 1024 16384 1523748 1 86 > 32768 4096 2048 16384 1522853 1 86 > > 16384 8192 0 32768 890911 3 147 > 16384 8192 512 32768 892026 3 146 > 16384 8192 1024 32768 890699 3 147 > 16384 8192 2048 32768 891862 3 146 > 16384 8192 4096 32768 889903 3 147 > > Obviously 34-sectors offset is bad for phybs. Write requests are NEVER get aligned. > I have recreated partition as follows: > > kibab-desktop# gpart delete -i 1 ad7 > ad7p1 deleted > kibab-desktop# gpart add -t freebsd-ufs -s 10G -b 63 ad7 > ad7p1 added > kibab-desktop# gpart show ad7 > => 34 2930277101 ad7 GPT (1.4T) > 34 29 - free - (15K) > 63 20971520 1 freebsd-ufs (10G) > 20971583 2909305552 - free - (1.4T) > > So, we have ad7p1 which is still misaligned, but if write request will start at offset=512, it will be aligned properly. > Let's test as follows: > > kibab-desktop# ./phybs -l 4096 -w /dev/ad7p1 > count size offset step msec tps kBps > > 32768 4096 0 16384 1520609 1 86 > 32768 4096 512 16384 17898 151 7323 > 32768 4096 1024 16384 1524899 1 85 > > :-) Aligned writes are 86 times faster than misaligned!!! > -- > Regards, > Ilya Bakulin > http://kibab.com > xmpp://kibab612@jabber.ru >
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