Date: Mon, 25 Nov 2013 10:18:30 -0800 From: Freddie Cash <fjwcash@gmail.com> To: Eric Browning <ericbrowning@skaggscatholiccenter.org> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: Performance difference between UFS and ZFS with NFS Message-ID: <CAOjFWZ5cDj2EVzft23vogUtv4jGSGM3RdL0wT_JfHjO-fgg-yw@mail.gmail.com> In-Reply-To: <CAM=5oeAPG0Vfa-fT1t=Vc8FS_jJGBiR=yq0wuUmEZYLYB%2Br7RA@mail.gmail.com> References: <2103733116.16923158.1384866769683.JavaMail.root@uoguelph.ca> <9F76D61C-EFEB-44B3-9717-D0795789832D@gmail.com> <CAM=5oeAF2gfccrGNdbApUDpqRae4OQjZ7oaZZi4y1j%2BsF6PsTw@mail.gmail.com> <5969250F-0987-4304-BB95-52C7BAE8D84D@gmail.com> <CAM=5oeBmCAq9unFGC2CBoJ3rZMm9MtDw1DWkFpo2ZqQtx3G%2B=Q@mail.gmail.com> <18391B9C-2FC4-427B-A4B6-1739B3C17498@gmail.com> <CAM=5oeAXiRn2aHvNPuZRPFJp6G45OqdQEDsz2_xGobCUHJp_VQ@mail.gmail.com> <CAM=5oeAybYZsn-TQTvfYO3Kx-chZULeYUEhg9fRMi-CFX0aYBA@mail.gmail.com> <B7C29F362A5045B48BF4CE223E7CE0AD@multiplay.co.uk> <CALfReyfDWTsgXf8JX-eNYOTFdkcYovUf0q=zGQPDUsEUi4nqbw@mail.gmail.com> <CAM=5oeAPG0Vfa-fT1t=Vc8FS_jJGBiR=yq0wuUmEZYLYB%2Br7RA@mail.gmail.com>
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On Mon, Nov 25, 2013 at 10:14 AM, Eric Browning < ericbrowning@skaggscatholiccenter.org> wrote: > I am using /dev/zero > > /usr/bin/time -h dd if=3D/dev/zero of=3Dsometestfile bs=3D1024 count=3D30= 00000 > You really shouldn't use /dev/zero to "benchmark" ZFS. It doesn't work the way you think it will, especially if dedupe or compression are enabled. Either use a proper filesystem benchmarking tool like iozone or bonnie++ or fio; or create a big file using /dev/random and then dd that file to various places in the filesystem.=E2=80=8B=E2=80=8B # =E2=80=8Bdd if=3D/dev/random of=3Dbigfile.100M bs=3D1M count=3D100=E2=80= =8B =E2=80=8BReboot to clear caches. Then use if=3Dbigfile.100M in your actual= testing.=E2=80=8B --=20 Freddie Cash fjwcash@gmail.com
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