From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wols Lists Subject: Re: [BUG] non-metadata arrays cannot use more than 27 component devices Date: Sat, 25 Feb 2017 23:55:51 +0000 Message-ID: <58B21987.6060604@youngman.org.uk> References: <20170224040816.41f2f372.ian_bruce@mail.ru> <41ea334c-ae1c-dac6-e1a1-480d3700a588@turmel.org> <20170224084024.4dfe83a2.ian_bruce@mail.ru> <1e40da0d-b175-9ff5-d2e5-cf1f25aacc26@turmel.org> <58B2137B.6070608@youngman.org.uk> <5172e2ab-e193-477b-52c4-86fbab0d52fe@turmel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5172e2ab-e193-477b-52c4-86fbab0d52fe@turmel.org> Sender: linux-raid-owner@vger.kernel.org To: Phil Turmel , ian_bruce@mail.ru, linux-raid@vger.kernel.org List-Id: linux-raid.ids On 25/02/17 23:41, Phil Turmel wrote: >> Is there a sound technical reason not to go there, or is it simply a >> > case of "learn another tool for that job"? The less tools I have to know >> > the better, imho. > Um, no, imnsho. Learn new tools when you need them. I don't have a problem with that. All too often people use the tool they're familiar with when it's the wrong tool. But there's a reason they do that - it's a familiar tool! > > Linux raid has no formal mechanism to cleanly separate a mirror from a > running array, access it as a backup, and not risk corruption when > re-attaching it to the array. Most filesystems write to the partition > when mounting, even for read-only mounts. You cannot safely access the > disconnected member except via pure block reads. Because to do so doesn't make sense? Or because nobody's bothered to do it? I get grumpy when people implement corner cases without bothering to implement the logically sensible options - bit like those extremely annoying dialog boxes that give you three choices, "yes", "no", "yes to all". What about no to all? I feel like mirror-raid is perfect for doing backups. I take your point that linux hasn't implemented that feature (particularly well), but surely it's a feature that *should* be there. I know I know - "patches welcome" :-) Cheers, Wol