Date: Sun, 13 Jul 2003 22:01:37 -0500 From: Marc Wiz <marc@wiz.com> To: "Greg 'groggy' Lehey" <grog@freebsd.org> Cc: freebsd-questions@freebsd.org Subject: Re: vinum and hot-swapping Message-ID: <20030714030137.GG50589@freshaire.wiz.com> In-Reply-To: <20030714021914.GR94666@wantadilla.lemis.com> References: <200307130245.h6D2j8HB000556@soth.ventu> <20030713191453.GF23909@dan.emsphone.com> <20030714003258.GP94666@wantadilla.lemis.com> <20030714015746.GE50589@freshaire.wiz.com> <20030714021914.GR94666@wantadilla.lemis.com>
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On Mon, Jul 14, 2003 at 11:49:14AM +0930, Greg 'groggy' Lehey wrote: > On Sunday, 13 July 2003 at 20:57:46 -0500, Marc Wiz wrote: > > On Mon, Jul 14, 2003 at 10:02:58AM +0930, Greg 'groggy' Lehey wrote: > >>> I don't believe vinum can optimize full-stripe writes, though, since > >>> FreeBSD can only do I/O in 64k max chunks, > >> > >> 128 kB. > > > > I thought physio was limited to 64 KB? The man page on dump states > > this. Please correct me if I am wrong. > > Physio is limited to MAXPHYS, which you'll find defined in > /usr/include/sys/param.h: > > #ifndef MAXPHYS > #define MAXPHYS (128 * 1024) /* max raw I/O transfer size */ > #endif > That's nice to know. What prevents it from being increased beyond 128K? > I've taken a look at the dump code (yuk!), and it no longer places any > limitation on the block size. I'll fix the man page. > Thanks. I have tried increasing the block size but going past 64K does not seem to help performance. I will have to check the dump code to see if it is limiting itself to a max of 64K. Thanks! Marc -- Marc Wiz marc@wiz.com Yes, that really is my last name.
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