From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ig0-f172.google.com ([209.85.213.172]:35516 "EHLO mail-ig0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752266AbbJOQkh (ORCPT ); Thu, 15 Oct 2015 12:40:37 -0400 Received: by igbkq10 with SMTP id kq10so139754404igb.0 for ; Thu, 15 Oct 2015 09:40:36 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <2402569.dCkKzGyGNU@hoefnix> <561EBC3D.8060004@bouton.name> Date: Thu, 15 Oct 2015 12:40:36 -0400 Message-ID: Subject: Re: RAID6 stable enough for production? From: Rich Freeman To: Chris Murphy Cc: Btrfs BTRFS Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Wed, Oct 14, 2015 at 9:47 PM, Chris Murphy wrote: > > For that matter, now that GlusterFS has checksums and snapshots... Interesting - I haven't kept up with that. Does it actually do end-to-end checksums? That is, compute the checksum at the time of storage, store the checksum in the metadata somehow, and ensure the checksum matches when data is retrieved? I forget whether it was glusterfs or ceph I was looking at, but some of those distributed filesystems will only checksum data while in transit, but not while it is at rest. So, if a server claims it has a copy of the file, then it is assumed to be a good copy and you never realize that even though you have 5 copies of that file distributed around the server you ended up using differs from the other 4. I'm also not sure if it supports an n+1/2 model like raid5/6, or if it is just a 2*n model like raid1. If I want to store 5TB of data with redundancy, I'd prefer to not need 10TB worth of drives to do it, regardless of how many systems they're spread across. -- Rich