From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: generating a Linux WWN? Date: Sat, 06 Oct 2007 10:36:20 -0400 Message-ID: <47079D64.3070000@garzik.org> References: <1191622146.3475.51.camel@localhost.localdomain> <20071005.151131.125883267.davem@davemloft.net> <1191622488.3475.54.camel@localhost.localdomain> <20071005.151711.112302061.davem@davemloft.net> <1191679870.3338.17.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:56323 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755515AbXJFOgk (ORCPT ); Sat, 6 Oct 2007 10:36:40 -0400 In-Reply-To: <1191679870.3338.17.camel@localhost.localdomain> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: James Bottomley Cc: David Miller , ltuikov@yahoo.com, lydianconcepts@gmail.com, mdr@sgi.com, James.Smart@emulex.com, linux-scsi@vger.kernel.org James Bottomley wrote: > My problem with auto generated is that it's provably impossible to > generate globally unique numbers for WWNs without some internal source > of uniqueness (I know sparcs have this in their serial number, but most > PCs unfortunately don't). > > I know the auto generated number can be statistically reasonably unique, > but sysadmins are lazy people. If they run into this problem, they'll > take the knob with the on/off switch rather than the think about the > problem and specify the full WWN; and then, being busy people, they'll > forget about it as "problem solved". When they do this, statistically > (and probably years later) there will be a cluster reboot where the > entire SAN simply collapses and no-one knows why ... the poor SAN > administrator will likely spend weeks working out the problem is. Why, if we give lazy administrators root access, that's all they'll use, and they will just think "problem solved" until a serious security issue arises that takes down the cluster. See how silly and un-Linux that logic is? In Linux, the admin has the power to make stupid decisions -- or to make informed decisions that disagree your rigid "an admin should never do that" line of thought. It's their hardware. You're also using the 1% case of a 1% case of a 1% case to argue against a feature that is useful in making things Just Work(tm). Jeff