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From: Matthew Wilcox <matthew@wil.cx>
To: Matthew Jacob <lydianconcepts@gmail.com>
Cc: ltuikov@yahoo.com, David Miller <davem@davemloft.net>,
	jeff@garzik.org, mdr@sgi.com, James.Smart@emulex.com,
	linux-scsi@vger.kernel.org
Subject: Re: generating a Linux WWN?
Date: Wed, 3 Oct 2007 21:33:26 -0600	[thread overview]
Message-ID: <20071004033326.GJ12049@parisc-linux.org> (raw)
In-Reply-To: <7579f7fb0710032023x6773075ga0342033e8f6f3a4@mail.gmail.com>

On Wed, Oct 03, 2007 at 08:23:14PM -0700, Matthew Jacob wrote:
> For smaller bit spaces like 64 bit WWNs, you cannot, as you correctly
> point out, generate reliably unique numbers all by youself. The
> closest you could probably come is using a type 5 WWN with a known
> single OUI and then use "seconds since January 1 2007" as a serial
> number in the 36 bit VID space that gives you about 8 years before it
> wraps- the likely collision rate here would be pretty low.

Unless you generate more than one WWN per second.  We could enforce that
by have an msleep(1000) in the WWN generator function ... which might
discourage people from using it except when they really had to ;-)
Of course, if you turn on two computers in the same zone at the same
time, you're still screwed.

-- 
Intel are signing my paycheques ... these opinions are still mine
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours.  We can't possibly take such
a retrograde step."

  parent reply	other threads:[~2007-10-04  3:33 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-09-27 10:04 generating a Linux WWN? Jeff Garzik
2007-09-27 13:55 ` Michael Reed
2007-09-27 14:04 ` James Smart
2007-09-27 14:16   ` Patrick_Boyd
2007-09-27 14:46     ` Matthew Wilcox
2007-09-27 15:07       ` Michael Reed
2007-09-27 15:12         ` Michael Reed
2007-09-27 23:40         ` Jeff Garzik
2007-09-27 22:48       ` Jeff Garzik
2007-10-01 10:56         ` Andi Kleen
2007-09-27 14:19   ` Jeff Garzik
2007-09-27 14:29     ` Michael Reed
2007-09-27 15:30       ` Douglas Gilbert
2007-09-27 22:32         ` Jeff Garzik
2007-09-27 23:12       ` Jeff Garzik
2007-10-02 23:47         ` Luben Tuikov
2007-10-03  0:35           ` Jeff Garzik
2007-10-03  3:45             ` Luben Tuikov
2007-10-03  4:15               ` Jeff Garzik
2007-10-03  5:12                 ` Luben Tuikov
2007-10-03  5:25                   ` Jeff Garzik
2007-10-03  5:31                     ` Luben Tuikov
2007-10-03  5:45                       ` Jeff Garzik
2007-10-03 14:59                         ` Douglas Gilbert
2007-10-03 16:16                           ` Jeff Garzik
2007-10-03 18:02                         ` Matthew Jacob
2007-10-03 18:09                           ` Jeff Garzik
2007-10-03 19:44                             ` Luben Tuikov
2007-10-03 20:25                               ` Jeff Garzik
2007-10-03 22:08                                 ` Luben Tuikov
2007-10-03 22:17                                   ` David Miller
2007-10-04  0:11                                     ` Luben Tuikov
2007-10-04  3:23                                       ` Matthew Jacob
2007-10-04  3:27                                         ` Jeff Garzik
2007-10-04  3:33                                         ` Matthew Wilcox [this message]
2007-10-05 22:09                                     ` James Bottomley
2007-10-05 22:11                                       ` David Miller
2007-10-05 22:14                                         ` James Bottomley
2007-10-05 22:17                                           ` David Miller
2007-10-05 22:41                                             ` Jeff Garzik
2007-10-05 22:49                                               ` David Miller
2007-10-05 22:52                                                 ` Jeff Garzik
2007-10-06 14:11                                             ` James Bottomley
2007-10-06 14:36                                               ` Jeff Garzik
2007-10-06 15:04                                                 ` James Bottomley
2007-10-06 15:23                                                   ` Jeff Garzik
2007-10-06 15:33                                                     ` James Bottomley
2007-10-06 15:42                                                       ` Jeff Garzik
2007-10-08 18:42                                                     ` Luben Tuikov
2007-10-07  2:48                                                   ` David Miller
2007-10-08 15:41                                                     ` Michael Reed
2007-10-08 18:34                                                 ` Luben Tuikov
2007-10-07  2:46                                               ` David Miller
2007-10-08 18:18                                       ` Luben Tuikov
2007-10-03  5:38                     ` Luben Tuikov
2007-10-03  5:47                       ` Jeff Garzik
2007-10-03 15:33                         ` Michael Reed
2007-10-03 16:02                           ` Jeff Garzik

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