From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from pigeon.gentoo.org ([208.92.234.80] helo=lists.gentoo.org) by finch.gentoo.org with esmtp (Exim 4.60) (envelope-from ) id 1RDlbN-0007Ng-Qq for garchives@archives.gentoo.org; Tue, 11 Oct 2011 23:19:14 +0000 Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 2AF5421C138; Tue, 11 Oct 2011 23:18:55 +0000 (UTC) Received: from mail-ww0-f53.google.com (mail-ww0-f53.google.com [74.125.82.53]) by pigeon.gentoo.org (Postfix) with ESMTP id DECF721C0A5 for ; Tue, 11 Oct 2011 23:17:15 +0000 (UTC) Received: by wwg14 with SMTP id 14so152169wwg.10 for ; Tue, 11 Oct 2011 16:17:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=date:from:to:subject:message-id:in-reply-to:references:organization :x-mailer:mime-version:content-type:content-transfer-encoding; bh=geVexM3Xc3V+4/bq6dC7+y+Dbkp0jsXdmgaBYbBDSBA=; b=K9HbVCWANJFkliya5LF6dKspTdESIKZL3Og9piBgyurjTCptwRP9FDtr1iBO5PjIvW yMYyFntaGbNK48zrxeSY8KnjkqQNm0UvFZ2LU0v4hnbCNJOcEeq4sMUz2SZq515JUn+f QsNM3DNK6Vv/HB8tr7bDzsSTYmOFXdbNdX8RU= Received: by 10.227.143.72 with SMTP id t8mr8272089wbu.95.1318375034842; Tue, 11 Oct 2011 16:17:14 -0700 (PDT) Received: from rohan.example.com ([196.215.144.38]) by mx.google.com with ESMTPS id k26sm305287wbo.16.2011.10.11.16.17.11 (version=SSLv3 cipher=OTHER); Tue, 11 Oct 2011 16:17:13 -0700 (PDT) Date: Wed, 12 Oct 2011 01:17:02 +0200 From: Alan McKinnon To: gentoo-user@lists.gentoo.org Subject: Re: [gentoo-user] SSDs, ext4, fstrim, discard ... Message-ID: <20111012011702.73eef020@rohan.example.com> In-Reply-To: <4E94C2F3.6000607@xunil.at> References: <4E94AD7F.7050405@xunil.at> <20111012000538.2ee0d7de@rohan.example.com> <4E94C2F3.6000607@xunil.at> Organization: Internet Solutions X-Mailer: Claws Mail 3.7.8 (GTK+ 2.24.4; x86_64-pc-linux-gnu) Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-user@lists.gentoo.org Reply-to: gentoo-user@lists.gentoo.org Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Archives-Salt: X-Archives-Hash: ccef7f7b97cb01933ef36b038be37cde On Wed, 12 Oct 2011 00:28:03 +0200 "Stefan G. Weichinger" wrote: > Am 12.10.2011 00:05, schrieb Alan McKinnon: > > > Yes, you misunderstand how fstrim works. It's not up to you to say > > what it does exactly, it's up to the drive firmware and possibly > > the kernel. It's actually fully described in the man page right > > there in the part for option -v :-) > > So it only tells me "something"? No, it's giving you a fact (and slightly misrepresenting it in the output). You asked the drive firmware for a favour - to please check if anything can be discarded and if so to discard it. The firmware checked that it *could* discard X bytes and then figured well, maybe it will, maybe it won't, maybe it'll do it on it's own good time, but what the heck - tell the user anyway how many bytes X is. Maybe that'll make the user happy so he'll stfu and go away...... The command leads you to believe the discard was actually done, but that's not necessarily true :-) It's probably a case of the drive knows much better than you what it should do. -- Alan McKinnnon alan.mckinnon@gmail.com