Date: Tue, 17 May 2016 22:28:22 +0100 From: Steven Hartland <steven@multiplay.co.uk> To: Freddie Cash <fjwcash@gmail.com> Cc: "Brandon J. Wandersee" <brandon.wandersee@gmail.com>, "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: ZFS performance bottlenecks: CPU or RAM or anything else? Message-ID: <CAHEMsqaBtjk2Zt%2BoLERT7xgrCNcR6YHBw044N3qaL6fUA==nuA@mail.gmail.com> In-Reply-To: <CAOjFWZ6o8Gqh1BzUbkLj%2BKKXm=r2S-3qy_yk5k84Q57yj7FuAw@mail.gmail.com> References: <8441f4c0-f8d1-f540-b928-7ae60998ba8e@lexa.ru> <f87ec54a-104e-e712-7793-86c37285fdaa@internetx.com> <16e474da-6b20-2e51-9981-3c262eaff350@lexa.ru> <BD7DE274-04EB-4B19-988D-5A6FADC5B51A@digsys.bg> <1e012e43-a49b-6923-3f0a-ee77a5c8fa70@lexa.ru> <86shxgsdzh.fsf@WorkBox.Home> <CAHEMsqZto0wD9Ko4E9YUpYvea4jM0E4f2nC1HkAwcCG=6DfX-A@mail.gmail.com> <CAOjFWZ6o8Gqh1BzUbkLj%2BKKXm=r2S-3qy_yk5k84Q57yj7FuAw@mail.gmail.com>
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Tbh if the results were from more than 6 months ago they are likely quite out of date as things have changed quite significantly in that period, so retesting would be advised. On Tuesday, 17 May 2016, Freddie Cash <fjwcash@gmail.com> wrote: > On Tue, May 17, 2016 at 2:11 PM, Steven Hartland <steven@multiplay.co.uk > <javascript:_e(%7B%7D,'cvml','steven@multiplay.co.uk');>> wrote: > >> Raidz is limited essential limited to a single drive performance >> per dev for read and write while mirror is single drive performance for >> write its number of drives for read. Don't forget mirror is not limited = to >> two it can be three, four or more; so if you need more read throughput y= ou >> can add drives to the mirror. >> >> To increase raidz performance you need to add more vdevs. While this >> doesn't have to be double i.e. the same vdev config as the first it >> generally a good idea. >> >> Don't forget that while it rebalances write performance of a multi vdev >> raidz will be limited to the added vdev. >> > > =E2=80=8BEverybody is missing the point of the OP. > > They're not asking for ways to improve the performance of a raidz-based > pool; they're asking why they get different performance metrics from the > exact same pool when they change the CPU and RAM. > > And, more importantly, why a Core-i3-based system shows better performanc= e > than a Core-i7-based system.=E2=80=8B Is there something inherent to the= way ZFS > works that favours one setup over another (lower CPU core counts running = at > higher speeds is better/worse than higher CPU core counts running at lowe= r > speeds; more RAM channels is better/worse; things like that). > > > -- > Freddie Cash > fjwcash@gmail.com <javascript:_e(%7B%7D,'cvml','fjwcash@gmail.com');> >
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