From owner-freebsd-hackers@FreeBSD.ORG Fri Sep 12 16:47:23 2008 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 063ED1065685 for ; Fri, 12 Sep 2008 16:47:23 +0000 (UTC) (envelope-from zbeeble@gmail.com) Received: from yw-out-2324.google.com (yw-out-2324.google.com [74.125.46.29]) by mx1.freebsd.org (Postfix) with ESMTP id AD31C8FC2C for ; Fri, 12 Sep 2008 16:47:22 +0000 (UTC) (envelope-from zbeeble@gmail.com) Received: by yw-out-2324.google.com with SMTP id 9so354253ywe.13 for ; Fri, 12 Sep 2008 09:47:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from:to :subject:cc:in-reply-to:mime-version:content-type:references; bh=wAseeKx8eg26UwtnNyvKmuW8HXV4KtQUh7xwICqQRus=; b=NFoZu2x9uqJNI9jkHTuBSSH9d2s1Gcmpz4oLrF6I9h2eB0J//MeJwUeuYDt2bFpzp0 8ivz4zTWqBWLy6iSqOqHmVAl98c7aYGepgUKwy+iLh6YpOH95+k2sbZzfmRfiwflKjHj 4Tgz2ZMxZNfP7Wrz8iOFLrD92Gd2oFonhLhy4= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:to:subject:cc:in-reply-to:mime-version :content-type:references; b=Z4PZe2LXT+okcepiTmt+8qSJbGwtPm1LfRcguSJYQvAQRjc/zQr5viI74DnTl/cIgt U4b/cOfTmhOipSQsR/yIFY5PEuOknYHo4GdyJRuY/T6r+1cChYuV2pZaWmGlEvSlNpZf 195yyDd0HZPC9jHcx+d9eauz4c0uKUL8O+5CI= Received: by 10.151.156.12 with SMTP id i12mr6314461ybo.217.1221238041367; Fri, 12 Sep 2008 09:47:21 -0700 (PDT) Received: by 10.150.137.11 with HTTP; Fri, 12 Sep 2008 09:47:21 -0700 (PDT) Message-ID: <5f67a8c40809120947u2bbeb03cnb20618e1d9ddf6b8@mail.gmail.com> Date: Fri, 12 Sep 2008 12:47:21 -0400 From: "Zaphod Beeblebrox" To: "Jeremy Chadwick" In-Reply-To: <20080912163207.GE60094@icarus.home.lan> MIME-Version: 1.0 References: <200809121544.m8CFiRHQ099725@lurza.secnetix.de> <5f67a8c40809120904o49b6e410l5b65a20f5216202@mail.gmail.com> <20080912163207.GE60094@icarus.home.lan> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: freebsd-hackers@freebsd.org, kpielorz_lst@tdx.co.uk Subject: Re: ZFS w/failing drives - any equivalent of Solaris FMA? X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Sep 2008 16:47:23 -0000 On Fri, Sep 12, 2008 at 12:32 PM, Jeremy Chadwick wrote: > On Fri, Sep 12, 2008 at 12:04:27PM -0400, Zaphod Beeblebrox wrote: > > On Fri, Sep 12, 2008 at 11:44 AM, Oliver Fromme >wrote: > > > Did you try "atacontrol detach" to remove the disk from > > > the bus? I haven't tried that with ZFS, but gmirror > > > automatically detects when a disk has gone away, and > > > doesn't try to do anything with it anymore. It certainly > > > should not hang the machine. After all, what's the > > > purpose of a RAID when you have to reboot upon drive > > > failure. ;-) > > > > To be fair, many "home" users run RAID without the expectation of being > able > > to hot swap the drives. While RAID can provide high availability, but it > > can also provide simple data security. > > RAID only ensures a very, very tiny part of "data security", and it > depends greatly on what RAID implementation you use. No RAID > implementation I know of provides against transparent data corruption > ("bit-rot"), and many RAID controllers and RAID drivers have bugs that Well... this is/was a thread about ZFS. ZFS does detect that bitrot _and_ correct it if it is possible. > A big problem is also that end-users *still* think RAID is a replacement > for doing backups Well... this comment seems a bit off topic, but maybe (in some cases) RAID is a substitute for doing backups. I suppose it depends on your tolerance and data value. The sheer size of some datasets these days makes backup prohibitively time consuming and/or expensive. Then again (this is a ZFS thread), ZFS helps with this: the ability to export snapshots to other spinning spool makes a lot of sense.