Re: [dm-devel] Re: Is there a grand plan for FC failover?

Philip R. Auld
2004-01-31T17:01:40Z

Rumor has it that on Sat, Jan 31, 2004 at 10:30:37AM +0100 Jens Axboe said:
> On Fri, Jan 30 2004, Joe Thornber wrote:
> > It would be great to get some benchmarks to back up these arguments.
> > eg, performance of dm mpath with a simple round robin selector,
> > compared to a scsi layer implementation. Lifting the elevator (or
> > lowering dm) is a big piece of work that I wont even consider unless
> > there is very good reason; the reason probably needs to be broader
> > than just multipath too. Even if we did decide to do this, it won't
> > happen in 2.6.
>
> I suspect the problem really isn't that huge in 2.6, since most
> performance file systems are using mpage or building their own big
> bio's. So in a sense, some of the merging already does happen above dm
> (and the io scheduler).

Out of curiosity, where does raw io fit into that in 2.6?

Thanks,

Phil

--
Philip R. Auld, Ph.D. Egenera, Inc.
Principal Software Engineer 165 Forest St.
(508) 858-2628 Marlboro, MA 01752