From owner-freebsd-questions Tue Sep 10 17:35:48 2002 Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.FreeBSD.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 7A88137B400 for ; Tue, 10 Sep 2002 17:35:45 -0700 (PDT) Received: from obsecurity.dyndns.org (adsl-64-165-226-88.dsl.lsan03.pacbell.net [64.165.226.88]) by mx1.FreeBSD.org (Postfix) with ESMTP id F407B43E3B for ; Tue, 10 Sep 2002 17:35:44 -0700 (PDT) (envelope-from kris@obsecurity.org) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id 811A466B62; Tue, 10 Sep 2002 17:35:44 -0700 (PDT) Date: Tue, 10 Sep 2002 17:35:44 -0700 From: Kris Kennaway To: "Jack L. Stone" Cc: freebsd-questions@freebsd.org Subject: Re: DD copy is too slow Message-ID: <20020911003544.GB77641@xor.obsecurity.org> References: <3.0.5.32.20020910183731.00fbeac8@mail.sage-one.net> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="H+4ONPRPur6+Ovig" Content-Disposition: inline In-Reply-To: <3.0.5.32.20020910183731.00fbeac8@mail.sage-one.net> User-Agent: Mutt/1.4i Sender: owner-freebsd-questions@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG --H+4ONPRPur6+Ovig Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Sep 10, 2002 at 06:37:31PM -0500, Jack L. Stone wrote: > Am running FBSD 4.5-RELEASE >=20 > On one of the servers, am having very slow real dd copy speed vs test and > don't know why. Below is the test first made that shows 25MB/s but the re= al > dd copy is only doing about half the speed. Other servers are matching the > test. Wonder what is wrong with this machine I/O....?? You've got double the disk I/O happening (read from ad0, write to ad1 _on the same IDE channel_). It won't be more than half the speed of a single-way transfer (and in fact is a bit less than half). You'll have better performance if you stick the drives on different channels or controllers. Kris --H+4ONPRPur6+Ovig Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.7 (FreeBSD) iD8DBQE9fo/fWry0BWjoQKURAsrNAJ4vO7ZoEn7j/Jla5g2s2pnAP1gCPgCgplPy RtGT9QTFqUVTxQdzaj0jwjo= =iTMH -----END PGP SIGNATURE----- --H+4ONPRPur6+Ovig-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message