From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from 220-245-31-42.static.tpgi.com.au ([220.245.31.42]:51665 "EHLO smtp.sws.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752646AbaEPDHJ (ORCPT ); Thu, 15 May 2014 23:07:09 -0400 Received: from xev.localnet (localhost [127.0.0.1]) by smtp.sws.net.au (Postfix) with ESMTP id CB39320797 for ; Fri, 16 May 2014 13:07:06 +1000 (EST) From: Russell Coker To: linux-btrfs@vger.kernel.org Reply-To: russell@coker.com.au Subject: ditto blocks on ZFS Date: Fri, 16 May 2014 13:07:05 +1000 Message-ID: <2308735.51F3c4eZQ7@xev> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: linux-btrfs-owner@vger.kernel.org List-ID: https://blogs.oracle.com/bill/entry/ditto_blocks_the_amazing_tape Probably most of you already know about this, but for those of you who haven't the above describes ZFS "ditto blocks" which is a good feature we need on BTRFS. The briefest summary is that on top of the RAID redundancy there is one more copy of metadata than there is of data, so copies=2 implies 3 copies of metadata and the default option of 1 copy of data means that metadata is "dup" in addition to whatever RAID redundancy is in place. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/