Messages in this thread | | | Date | Fri, 14 Feb 2003 10:17:44 -0800 | From | Patrick Mansfield <> | Subject | Re: Accessing the same disk via multiple channels |
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On Fri, Feb 14, 2003 at 05:27:22PM +0100, Lars Marowsky-Bree wrote:
> Indeed. Yes, we'll need to figure out how to do this for 2.5/2.6; maybe > porting forward the md m-p patch to 2.5 is indeed the best choice. It should > be way easier, as md has been greatly cleaned up...
> However, past discussions on LKML regarding "How to do m-p cleanly in 2.5" > have never reached a conclusion ;-) We'll see. The good thing about the SCSI > m-p is that it can also handle multipathed tape drives...
I thought the general consensus was it is OK for now (as a first go) to have scsi only multi-path, I have not heard anyone say don't do scsi multi-path. And then later (maybe after we have more than one subsystem supporting multi-path IO) we can add general multi-path support into the layers above scsi.
In any case, md or volume manager based multi-path solutions are good alternatives.
I have recently ported the scsi multi-path patch to 2.5.59, but haven't posted patches.
The current multi-path patch still needs at least two major changes in scsi: error recovery (scsi_error.c) that allows other paths to be used without long delays, and a per-device queue_lock versus the current per-host queue_lock.
Hopefully we can get underlying changes for those last two into 2.5 (and maybe someday the multi-path patch), as they are improvements to scsi with or without multi-path.
-- Patrick Mansfield - 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/
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