From owner-freebsd-questions@freebsd.org Mon Aug 31 13:41:08 2015 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BB9869C6929 for ; Mon, 31 Aug 2015 13:41:08 +0000 (UTC) (envelope-from quartz@sneakertech.com) Received: from douhisi.pair.com (douhisi.pair.com [209.68.5.179]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 9C66D1806 for ; Mon, 31 Aug 2015 13:41:08 +0000 (UTC) (envelope-from quartz@sneakertech.com) Received: from [10.2.2.1] (pool-173-48-121-235.bstnma.fios.verizon.net [173.48.121.235]) by douhisi.pair.com (Postfix) with ESMTPSA id 994A23F6FB for ; Mon, 31 Aug 2015 09:41:07 -0400 (EDT) Message-ID: <55E45973.2050103@sneakertech.com> Date: Mon, 31 Aug 2015 09:41:07 -0400 From: Quartz MIME-Version: 1.0 To: freebsd-questions@freebsd.org Subject: Re: Replacing Drive with SSD References: <20150829220311.c7608be1.freebsd@edvax.de> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 31 Aug 2015 13:41:08 -0000 > Making a partition for free space is one way. Another way is to leave > part of the drive unpartitioned. Either one just guarantees there is a > good supply of unused blocks available to the drive. I'm not super well versed on exactly how SSD TRIM works. How does the drive in question know which blocks are or aren't free, isn't that a function of the filesystem? For that matter, how does the drive even "know" which parts are or aren't partitioned, it's not like they're programmed to understand MBR vs GPT, etc. How does the system communicate to the drive firmware layer which blocks are in use? Simply assuming based on if or how long ago it was written to can't possibly be a workable solution. I'm not convinced that leaving large chunks of the drive 'free' has any effect on wear leveling.