Date: Tue, 15 Mar 2011 23:22:52 +0100 From: Polytropon <freebsd@edvax.de> To: Adam Vande More <amvandemore@gmail.com> Cc: freebsd_user@guice.ath.cx, freebsd-questions@freebsd.org Subject: Re: IDE -- mount partitions for better performance Message-ID: <20110315232252.c3114070.freebsd@edvax.de> In-Reply-To: <AANLkTikPiHwLLjCQVHWQTsPLVNVOkPvo%2Bx_d2Caj6UYd@mail.gmail.com> References: <8a6023db5a3d4c8b34161f7ee0af29bb.squirrel@wtp1.ath.cx> <201103151041.56373.erich@alogreentechnologies.com> <5ab7e13805185464a4adf0c5d326671e.squirrel@wtp1.ath.cx> <20110315215907.f8a08352.freebsd@edvax.de> <AANLkTikPiHwLLjCQVHWQTsPLVNVOkPvo%2Bx_d2Caj6UYd@mail.gmail.com>
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On Tue, 15 Mar 2011 17:07:20 -0500, Adam Vande More <amvandemore@gmail.com> wrote: > Your statement about master being faster than a slave is simply not true for > almost every scenario when using devices with same capabilites. All > master/slave really controls is enumeration, and shouldn't effect > performance in and of itself. Other variables can effect that of course, > like using a slower device as an ATA Device-1 with a faster Device-0. Even > that example isn't ubiquitous as many, maybe most controllers are able to > support mixed devices each in their fastest mode. My statement originates back from individual experience in settings where disks with different capabilities (esp. very old + very new disk), as well as disk drive and an optical drive with limited speed. > The whole IDE device contention really isn't much of a bottle neck in this > scenario. It's only a big factor when there's *a lot* of simultaneous IO > going to both, say dumping one disk to another. That's true: When copying (or moving) data from one disk to the other master->master seems to be faster than master->slave (same line), if I remember correctly. > The highest preforming setup in something like this is likely to be > something along the lines of a 4-way /boot gmirror, and a 4-way gstripe with > a smaller stripe size eg 32k across the remaining usable space. If you > aggregate your disk IO in this manner, IDE channel contention shouldn't be > much of a bottleneck. A good advice, I haven't thought of that (never tried, but sounds achievable). -- Polytropon Magdeburg, Germany Happy FreeBSD user since 4.0 Andra moi ennepe, Mousa, ...
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