From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f172.google.com ([209.85.223.172]:32904 "EHLO mail-io0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752060AbcJLLZE (ORCPT ); Wed, 12 Oct 2016 07:25:04 -0400 Received: by mail-io0-f172.google.com with SMTP id q192so47436884iod.0 for ; Wed, 12 Oct 2016 04:25:04 -0700 (PDT) Subject: Re: raid levels and NAS drives To: Nicholas D Steeves References: <20161011221031.GB5515@DigitalMercury.dynalias.net> Cc: Charles Zeitler , linux-btrfs@vger.kernel.org From: "Austin S. Hemmelgarn" Message-ID: <5dd67e2b-49fe-6f45-ad31-f1a75fc7b80c@gmail.com> Date: Wed, 12 Oct 2016 07:25:00 -0400 MIME-Version: 1.0 In-Reply-To: <20161011221031.GB5515@DigitalMercury.dynalias.net> Content-Type: text/plain; charset=windows-1252; format=flowed Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 2016-10-11 18:10, Nicholas D Steeves wrote: > On Mon, Oct 10, 2016 at 08:07:53AM -0400, Austin S. Hemmelgarn wrote: >> On 2016-10-09 19:12, Charles Zeitler wrote: >>> Is there any advantage to using NAS drives >>> under RAID levels, as oppposed to regular >>> 'desktop' drives for BTRFS? > [...] >> So, as for what you should use in a RAID array, here's my specific advice: >> 1. Don't worry about enterprise drives unless you've already got a system >> that has them. They're insanely overpriced for relatively minimal benefit >> when compared to NAS drives. >> 2. If you can afford NAS drives, use them, they'll get you the best >> combination of energy efficiency, performance, and error recovery. >> 3. If you can't get NAS drives, most desktop drives work fine, but you will >> want to bump up the scsi_command_timer attribute in the kernel for them (200 >> seconds is reasonable, just make sure you have good cables and a good >> storage controller). >> 4. Avoid WD Green drives, without special effort, they will get worse >> performance and have shorter lifetimes than any other hard disk I've ever >> seen. >> 5. Generally avoid drives with a capacity over 1TB from manufacturers other >> than WD, HGST, and Seagate, most of them are not particularly good quality >> (especially if it's an odd non-power-of-two size like 5TB). > > +1 ! Additionally, is it still the case that it is generally safer to > buy the largest capacity disks offered by the previous generation of > technology rather than the current largest capacity? eg: right now > that would be 4TB or 6TB, and not 8TB or 10TB. In general, yes, but you're normally safe as long as you're not using SMR disks. I've used a couple of 8TB non-SMR drives, and they work perfectly fine (although they're insanely expensive), it's just been the SMR stuff that's been an issue (and you shouldn't be using them for non-archival storage anyway).