Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 10 Sep 2002 13:23:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 10 Sep 2002 13:23:09 -0400 Received: from e4.ny.us.ibm.com ([32.97.182.104]:30193 "EHLO e4.ny.us.ibm.com") by vger.kernel.org with ESMTP id ; Tue, 10 Sep 2002 13:23:07 -0400 Subject: Re: [RFC] Multi-path IO in 2.5/2.6 ? [OFF TOPIC] To: Christoph Hellwig Cc: alan@lxorguk.ukuu.org.uk, linux-kernel@vger.kernel.org, lmb@suse.de X-Mailer: Lotus Notes Release 5.0.5 September 22, 2000 Message-ID: From: "Ben Rafanello" Date: Tue, 10 Sep 2002 12:27:03 -0500 X-MIMETrack: Serialize by Router on D01ML072/01/M/IBM(Release 5.0.11 |July 29, 2002) at 09/10/2002 01:27:05 PM MIME-Version: 1.0 Content-type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2302 Lines: 62 On Tue, 2002-09-10 at 11:33, Christoph Hellwig wrote: >> Support at least 1024 disks >> Support at least 1024 volumes >> Support at least 32 partitions per disk > >At least those criterias aren't archived. EVMS has no design limit on the number of disks that it can support, and, the way it is coded, the only limiting factor on the number of disks it can support is the amount of memory available. Any limits on the number of disks that EVMS can use come from Linux itself, and, as such, are beyond the control of the EVMS Team. We are not out to rewrite the kernel and the device drivers - we are just trying to meet the requirements we were given. As for 1024 volumes, that limit is due to the fact that EVMS has only 1 major number, as discussed in the original post. If EVMS were allowed more major numbers, then this criteria could be reached or exceeded. However, we thought it extremely unlikely that EVMS would be given enough major numbers under 2.4x to reach this goal, so we coded accordingly. Should a miracle occur and EVMS be given another three major numbers, we could easily update our code to make use of these extra major numbers and achieve 1023 volumes. As for partitions, EVMS has no fixed limit on the number of partitions per disk. The limit for partitions on a disk depends upon the size of the disk and the disk partitioning scheme used. I currently run a stress test on EVMS where I create 405 partitions on a single SCSI disk. These partitions are then combined in various ways to form volumes, which are then formatted and have I/O tests performed on them. All 405 partitions are used. Under EVMS, you could take any of those partitions and turn it into a volume, which makes it accessible. The only limit on EVMS is the number of volumes it can create, and this is due to EVMS having only 1 major number under 2.4x. So not only did we meet this requirement, we greatly exceeded this requirement. Regards, Ben Rafanello EVMS Team Lead IBM Linux Technology Center (512) 838-4762 benr@us.ibm.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/