From owner-freebsd-scsi@FreeBSD.ORG Fri Apr 19 17:58:03 2013 Return-Path: Delivered-To: freebsd-scsi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id F1075D21 for ; Fri, 19 Apr 2013 17:58:03 +0000 (UTC) (envelope-from kevin@your.org) Received: from mail.your.org (mail.your.org [IPv6:2001:4978:1:2::cc09:3717]) by mx1.freebsd.org (Postfix) with ESMTP id BA16DB69 for ; Fri, 19 Apr 2013 17:58:03 +0000 (UTC) Received: from mail.your.org (chi02.mail.your.org [204.9.55.23]) by mail.your.org (Postfix) with ESMTP id 52836F06C37; Fri, 19 Apr 2013 17:58:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=your.org; h=content-type :mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; s= selector1; bh=pZ4m0XtjkFr+raSy3LsbfBuZDr0=; b=DiGwj8AgSHhXFHsR2C 2RK2OhAdiOydJknz6OlQ5mO/RI4gPhsJftJRsNBXg5jmwNEUxWNxvx90V5BeMQHo RdnROcaILHHPNBmUMqTROH1IcXJXbimU+o27sjpuXBZovd0G7vcTCPX8dOmhPg/u f5RGHll/ALD3mvc0pau/IVMSo= DomainKey-Signature: a=rsa-sha1; c=nofws; d=your.org; h=content-type :mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; q=dns; s= selector1; b=NRDu9ktidUBSq/gy/C/IV0tTtF34Fw3+xaAbl2qkuzIgo7vk0XO Yb74vwf4Gpg4UYdDeVAV7TeuydxFVmG+awkw0SlIJ28WthndEswZC/7iJNRbdAuN DmEscwlwd9csxVSKce8RITKABCdVWdMQsTRTebmR2z/TfjSWGi8kVPDk= Received: from vpn132.rw1.your.org (vpn132.rw1.your.org [204.9.51.132]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by mail.your.org (Postfix) with ESMTPSA id F07F0F06C29; Fri, 19 Apr 2013 17:58:02 +0000 (UTC) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: New Driver for MegaRaid 6Gb/s and 12Gb/s Card From: Kevin Day In-Reply-To: Date: Fri, 19 Apr 2013 12:58:01 -0500 Content-Transfer-Encoding: quoted-printable Message-Id: <37C12059-AF0B-47C1-AD8E-1D3B4663CD3D@your.org> References: <1366236517.1499.31.camel@localhost> <516FF87E.8030702@freebsd.org> To: Scott Long X-Mailer: Apple Mail (2.1503) Cc: freebsd-scsi@freebsd.org X-BeenThere: freebsd-scsi@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: SCSI subsystem List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Apr 2013 17:58:04 -0000 On Apr 19, 2013, at 10:59 AM, Scott Long wrote: >=20 > What will the exposed device names of the arrays be under the new = driver? Will it still be /dev/mfid* ? If it's not, then this is where = the problem lies. Many users still use device names in their /etc/fstab = for mounting all of their filesystems at boot. If you have two drivers = that will compete for the same hardware and give that hardware different = names, they will break the fstab files for those users and they upgrade = over time. A similar situation occurred several years ago with the = Intel e1000 driver; it was split into two drivers, with certain hardware = that was supported by the old hardware going to the new driver. That = broke the network configuration for many users and caused years of pain = and unhappiness as users upgraded and were hit by the switch. We don't = want that to happen here. >=20 > The real solution is that we need to have a single common naming = convention for all disks (and for network interfaces), and leave the = details of individual driver names out of the configuration part of the = system. That's not likely to happen any time soon. The other solution = is to mandate that users use volume labels for mounting their = filesystems, but that's not likely to happen either, and even if it did, = it present challenges for migrating existing users. The only remaining = solution that I can think of is to have the mfi and mrsas drivers share = the same devclass for their disk interfaces (mfid*), but that's a hack = that has not been fully explored in FreeBSD. Still, I'd encourage you = to try it and see if you can make it work. If you have any problems, = email me directly. Some Linux distributions had a flag day where upgrading beyond a certain = point caused a one-time popup asking if you wanted to convert /etc/fstab = to volume labels instead of device names. You could say no and proceed = normally, but if you said Yes it rewrote fstab to use labels. I'm not = sure where we could hook this so it happened both with freebsd-update = and source upgrades, but it would be nice to make it painless to switch.