Date: Sat, 30 Dec 2006 00:30:25 -0600 From: Eric Anderson <anderson@centtech.com> To: Ivan Voras <ivoras@fer.hr> Cc: freebsd-geom@freebsd.org Subject: Re: gstripe performance scaling with many disks Message-ID: <45960781.3040304@centtech.com> In-Reply-To: <en12b6$l2e$2@sea.gmane.org> References: <20061228171858.GA11296@qlovarnika.bg.datamax> <en125k$l2e$1@sea.gmane.org> <en12b6$l2e$2@sea.gmane.org>
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On 12/28/06 12:27, Ivan Voras wrote: > Ivan Voras wrote: > >> I'll take a shot at this: Since maximum kernel reads are still limited >> to 128 KB/s, by adding more drives you're making individual requests >> shorter. I.e. with one drive, it gets 128 KB requests, with two, each >> gets 64 KB, with 16, each gets 8 KB. So network & kernel latency becomes >> visible. > > Btw. if I'm right, you should be able to observe this with gstat and/or > iostat. If you don't see it, then it's possible I'm wrong :) Maybe this should be tried with md* devices just to remove the network component from this mix. Eric -- ------------------------------------------------------------------------ Eric Anderson Sr. Systems Administrator Centaur Technology An undefined problem has an infinite number of solutions. ------------------------------------------------------------------------
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