From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:55631 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757172Ab2EVVrz (ORCPT ); Tue, 22 May 2012 17:47:55 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1SWwvo-0003YN-T3 for linux-btrfs@vger.kernel.org; Tue, 22 May 2012 23:47:52 +0200 Received: from cpc4-stap10-2-0-cust490.12-2.cable.virginmedia.com ([217.137.143.235]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 22 May 2012 23:47:52 +0200 Received: from m_btrfs by cpc4-stap10-2-0-cust490.12-2.cable.virginmedia.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Tue, 22 May 2012 23:47:52 +0200 To: linux-btrfs@vger.kernel.org From: Martin Subject: SSD erase state and reducing SSD wear Date: Tue, 22 May 2012 22:47:42 +0100 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Sender: linux-btrfs-owner@vger.kernel.org List-ID: I've got two recent examples of SSDs. Their pristine state from the manufacturer shows: Device Model: OCZ-VERTEX3 # hexdump -C /dev/sdd 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 1bf2976000 Device Model: OCZ VERTEX PLUS (OCZ VERTEX 2E) # hexdump -C /dev/sdd 00000000 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| * df99e6000 What's a good way to test what state they get erased to from a TRIM operation? Can btrfs detect the erase state and pad unused space in filesystem writes with the same value so as to reduce SSD wear? Regards, Martin