From owner-freebsd-questions@FreeBSD.ORG Fri Jun 13 14:16:43 2008 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 18EF81065670 for ; Fri, 13 Jun 2008 14:16:43 +0000 (UTC) (envelope-from kirk@strauser.com) Received: from kanga.honeypot.net (kanga.honeypot.net [206.29.77.83]) by mx1.freebsd.org (Postfix) with ESMTP id B0E018FC2C for ; Fri, 13 Jun 2008 14:16:42 +0000 (UTC) (envelope-from kirk@strauser.com) Received: from localhost (localhost [127.0.0.1]) by kanga.honeypot.net (Postfix) with ESMTP id AF7AD5DDEBA; Fri, 13 Jun 2008 09:00:08 -0500 (CDT) X-Virus-Scanned: amavisd-new at honeypot.net Received: from kanga.honeypot.net ([127.0.0.1]) by localhost (kanga.honeypot.net [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ceI6T8WYR4GH; Fri, 13 Jun 2008 09:00:06 -0500 (CDT) Received: from janus.daycos.com (janus.daycos.com [10.45.12.2]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by kanga.honeypot.net (Postfix) with ESMTPSA id 120875DDE67; Fri, 13 Jun 2008 09:00:06 -0500 (CDT) From: Kirk Strauser To: FreeBSD Questions Date: Fri, 13 Jun 2008 09:00:03 -0500 User-Agent: KMail/1.9.9 References: <200806121521.16237.kirk@strauser.com> In-Reply-To: X-Face: T+/_{qmjgbosI0J/e83I~w[&VF'w)!((xEpj///^bA/6?jHHS?nq+T8_+`nh"WnEWCWG, \}]Y2$)) =?utf-8?q?vLVz4ACChrEcb=7DCO=5EtYmMG=5C=0A=09ts=2Em=3F=5B7=5B6OwE*dAJ*9f+m?= =?utf-8?q?X=2E7R32qeN=5EDJ=5C?=(k@evW?IRQCy.^ MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart9009478.pBsXDSiXXg"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200806130900.04230.kirk@strauser.com> Cc: freebsd-questions@freebsd.org Subject: Re: Stripe sizes with gstripe X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 13 Jun 2008 14:16:43 -0000 --nextPart9009478.pBsXDSiXXg Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline On Thursday 12 June 2008, David Kelly wrote: > Apparently it won't read anything larger than your stripe size which > defaults to a miserable 4k. Ugh. It seems like there are a few possibilities here, and I'm not sure=20 which is actually true. Say you have two drives, striped. 1) Ideally, you could have a 512 byte stripe size. A program tries to read= =20 4KB. Then, gstripe would issue a single request to each drive to read 4=20 blocks and interleaves the results. 2) Less ideally, you'd have a 128KB stripe size. A program requests a=20 single block, but gstripe reads the entire stripe to fulfill the request. = =20 Not so hot for random access. 3) Worst, maybe? You have a 512 byte stripe. A program reads 4KB. gstrip= e=20 reads 512B from da0, then 512B from da1, then 512B from da0, etc. Actually, I guess you could also have a combination of #2 and #3, where=20 small reads fetch an entire stripe while large reads are broken into lots=20 of tiny ones. So, back to gstripe. Which of those is it most like? > If there is a tuning knob that I have missed, would appreciate being > told what. Pass it along, would ya? :-) Oh, and don't forget to make your partition offsets =2D-=20 Kirk Strauser --nextPart9009478.pBsXDSiXXg Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part. -----BEGIN PGP SIGNATURE----- iD8DBQBIUn1k5sRg+Y0CpvERAugsAJ45Zrb8PFmjEgllkqgC5LN4SrfliACeJS8q 3crRJeZbYwKEP7geX6PShdM= =KFNB -----END PGP SIGNATURE----- --nextPart9009478.pBsXDSiXXg--