From owner-freebsd-current@FreeBSD.ORG Sun Dec 11 01:42:02 2011 Return-Path: Delivered-To: current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 852F61065672 for ; Sun, 11 Dec 2011 01:42:02 +0000 (UTC) (envelope-from maksim.yevmenkin@gmail.com) Received: from mail-gx0-f182.google.com (mail-gx0-f182.google.com [209.85.161.182]) by mx1.freebsd.org (Postfix) with ESMTP id 4D8208FC0C for ; Sun, 11 Dec 2011 01:42:02 +0000 (UTC) Received: by ggnp1 with SMTP id p1so6162412ggn.13 for ; Sat, 10 Dec 2011 17:42:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; bh=/7UiUuUf4TY/lhcYrrvFjucirai96sOitqKbbXQcxsM=; b=QJham8q/+qn/d4dR2B5WCE3apPJvYrY/eKHGDDgWlOKuAk11VRgw6IIWHykhMkfOXh ObZRtaDEoXpXUxI7m7vvFAsqVlrxTyN3iGaPUtqAyY/CqtreXvYaSOOtloJ3hOwnxRr+ xWojPN+TWx2RA6Xi+kVwsiTwMfxKWw+0BclsM= MIME-Version: 1.0 Received: by 10.101.160.5 with SMTP id m5mr3127972ano.3.1323567721730; Sat, 10 Dec 2011 17:42:01 -0800 (PST) Received: by 10.100.93.8 with HTTP; Sat, 10 Dec 2011 17:42:01 -0800 (PST) Date: Sat, 10 Dec 2011 17:42:01 -0800 Message-ID: From: Maksim Yevmenkin To: current@freebsd.org Content-Type: text/plain; charset=ISO-8859-1 Cc: Subject: calling all fs experts X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 11 Dec 2011 01:42:02 -0000 Hello, i have a question for fs wizards. suppose i can persuade modern spinning disk to do "large" reads (say 512K to 1M) at a time. also, suppose file system on such modern spinning drive is used to store large files (tens to hundreds of megabytes). is there any way i can tweak the file system parameters (block size, layout, etc) to help it to get as close to "disk's sequential read rate" as possible. I understand that i will not be able to get 100MB/sec single client sequential read rate, but, can i get it into sustained 40-50MB/sec rate? also, can i reduce performance impact caused by "small reads" such as directory access etc. thanks, max