From owner-freebsd-stable@FreeBSD.ORG Mon Feb 19 19:51:44 2007 Return-Path: X-Original-To: freebsd-stable@freebsd.org Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id A2F0216C6D4 for ; Mon, 19 Feb 2007 19:51:44 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from elvis.mu.org (elvis.mu.org [192.203.228.196]) by mx1.freebsd.org (Postfix) with ESMTP id 8F8D313C442 for ; Mon, 19 Feb 2007 19:51:44 +0000 (UTC) (envelope-from kris@obsecurity.org) Received: from obsecurity.dyndns.org (elvis.mu.org [192.203.228.196]) by elvis.mu.org (Postfix) with ESMTP id 761E81A3C1A; Mon, 19 Feb 2007 11:51:44 -0800 (PST) Received: by obsecurity.dyndns.org (Postfix, from userid 1000) id B540F54070; Mon, 19 Feb 2007 14:51:43 -0500 (EST) Date: Mon, 19 Feb 2007 14:51:43 -0500 From: Kris Kennaway To: Volker Message-ID: <20070219195143.GA42379@xor.obsecurity.org> References: <45D9FD35.6040702@vwsoft.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45D9FD35.6040702@vwsoft.com> User-Agent: Mutt/1.4.2.2i Cc: freebsd-stable@freebsd.org Subject: Re: getting garbage faster using FreeBSD? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 Feb 2007 19:51:44 -0000 On Mon, Feb 19, 2007 at 08:40:37PM +0100, Volker wrote: > Hi! > > For my dentist I'm currently in the process of destroying some tape > cartridges (SLR7) and also two hard disks (147G SCSI). > > As I started for the tapes, I've used dd to fill the tape with > random garbage. Just a simple `dd if=/dev/random of=/dev/nsa0'. > > The tape sits there since 48 hours writing a block of data every > other minute and still didn't fill up the tape completely. The > system this is running on is a P-4 3GHz machine using FreeSBIE 2.0 > (6.2-RELEASE based). > > I suspect this to be a slow /dev/random. This sounds odd to me, I get 18-20MB/sec sustained read performance from /dev/random on this 2GHz system, which is probably faster than your tape write speed. > Is there any chance to speed up /dev/random? Would a hifn > accelerator card help here to get FreeBSD produce garbage faster? > > As there is medical data on all media I really need garbage > (/dev/zero wouldn't be enough for data security as this might get > recovered). Neither would a single pass with /dev/random, but you presumably knew this. Kris