From owner-freebsd-questions@FreeBSD.ORG Tue Dec 2 21:14:07 2008 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 191CB106564A for ; Tue, 2 Dec 2008 21:14:07 +0000 (UTC) (envelope-from wojtek@wojtek.tensor.gdynia.pl) Received: from wojtek.tensor.gdynia.pl (wojtek.tensor.gdynia.pl [IPv6:2001:4070:101:2::1]) by mx1.freebsd.org (Postfix) with ESMTP id BE02C8FC0C for ; Tue, 2 Dec 2008 21:14:04 +0000 (UTC) (envelope-from wojtek@wojtek.tensor.gdynia.pl) Received: from wojtek.tensor.gdynia.pl (localhost [IPv6:::1]) by wojtek.tensor.gdynia.pl (8.14.3/8.14.3) with ESMTP id mB2LDmMj016812; Tue, 2 Dec 2008 22:13:48 +0100 (CET) (envelope-from wojtek@wojtek.tensor.gdynia.pl) Received: from localhost (wojtek@localhost) by wojtek.tensor.gdynia.pl (8.14.3/8.14.3/Submit) with ESMTP id mB2LDmY2016809; Tue, 2 Dec 2008 22:13:48 +0100 (CET) (envelope-from wojtek@wojtek.tensor.gdynia.pl) Date: Tue, 2 Dec 2008 22:13:48 +0100 (CET) From: Wojciech Puchar To: "Anthony M. Rasat" In-Reply-To: <189164649-1228250848-cardhu_decombobulator_blackberry.rim.net-2111088666-@bxe1001.bisx.prodap.on.blackberry> Message-ID: <20081202220948.T16797@wojtek.tensor.gdynia.pl> References: <189164649-1228250848-cardhu_decombobulator_blackberry.rim.net-2111088666-@bxe1001.bisx.prodap.on.blackberry> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-questions@freebsd.org Subject: Re: Swapping to MMC (Was: To swap or not to swap) 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: Tue, 02 Dec 2008 21:14:07 -0000 > > I put in your opinions in kinda pros or cons to swap in Asus Eee PC like following: > > Pros: 1) System requires swap. Period. it doesn't. > Cons: 1) Since SSD is manufactured have limited lifetime (around 100,000 10000 for MLC flash it uses. after every rewrite flash gets less reliable and keeps data for shorter time. new flash chip guarrantes 10 years data persistency using standard error correction, after 9000 rewrites it's about 1 year etc. and: SSD "disks" emulates disks instead of using flash-designed filesystem. they do LOTS of extra writes for "worn up management", mapping tables. you can safely assume 2 times more data written in reality than requested. assuming 4GB flash, 10000*4GB/2=20TB of writes and flash is dead. not that much with swapping IO ranged in megabytes/s