From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Jeff Garzik <jeff@garzik.org>
Cc: Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk>,
Anthony Liguori <aliguori@us.ibm.com>,
Chris Wright <chrisw@sous-sol.org>,
virtualization@lists.osdl.org, xen-devel@lists.xensource.com,
linux-kernel@vger.kernel.org, Ian Pratt <ian.pratt@xensource.com>,
ian.pratt@cl.cam.ac.uk,
SCSI Mailing List <linux-scsi@vger.kernel.org>
Subject: Re: [RFC PATCH 35/35] Add Xen virtual block device driver.
Date: Fri, 24 Mar 2006 12:17:53 +0000 [thread overview]
Message-ID: <1143202673.18986.5.camel@localhost.localdomain> (raw)
In-Reply-To: <4421D943.1090804@garzik.org>
On Mer, 2006-03-22 at 18:09 -0500, Jeff Garzik wrote:
> An IBM hypervisor on ppc64 communicates uses SCSI RPC messages. I think
> this would be quite nice for Xen, because SCSI (a) is a message-based
> model, and (b) implementing block using SCSI has a very high Just
> Works(tm) value which cannot be ignored. And perhaps (c) SCSI target
> code already exists, so implementing the server side doesn't require
> starting from scratch, but rather simply connecting the Legos.
A pure SCSI abstraction doesn't allow for shared head scheduling which
you will need to scale Xen sanely on typical PC boxes. SCSI emulations
are also always full of bits people got wrong, often critical bits like
tagged queues and error sequences - things that break your journalled
file system.
next prev parent reply other threads:[~2006-03-24 12:11 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <A95E2296287EAD4EB592B5DEEFCE0E9D4B9E8A@liverpoolst.ad.cl.cam.ac.uk>
2006-03-22 23:09 ` [RFC PATCH 35/35] Add Xen virtual block device driver Jeff Garzik
2006-03-24 12:17 ` Alan Cox [this message]
2006-03-24 12:38 ` Jeff Garzik
2006-03-24 13:37 ` Jeff Garzik
2006-03-24 13:40 ` Arjan van de Ven
2006-03-24 13:50 ` Jeff Garzik
2006-03-24 15:33 ` Dave C Boutcher
2006-03-24 19:04 ` Mike Christie
2006-03-24 19:19 ` Dave C Boutcher
2006-03-25 0:32 ` FUJITA Tomonori
2006-03-25 0:47 ` Roland Dreier
2006-03-24 15:55 ` Alan Cox
2006-03-25 10:03 ` Rusty Russell
2006-03-27 10:14 ` Peter Chubb
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