[dm-devel] dm-multipath: Accept failed paths for multipath maps
Mike Snitzer
snitzer at redhat.com
Wed Dec 18 14:08:58 UTC 2013
On Wed, Dec 18 2013 at 2:52am -0500,
Hannes Reinecke <hare at suse.de> wrote:
> The multipath kernel module is rejecting any map with an invalid
> device. However, as the multipathd is processing the events serially
> it will try to push a map with invalid devices if more than one
> device failed at the same time.
> So we can as well accept those maps and make sure to mark the
> paths as down.
Why is it so desirable to do this? Reduced latency to restore at least
one valid path when a bunch of paths go down?
Why can't we just rely on userspace eventually figuring out which paths
are failed and pushing a valid map down?
Are there favorable reports that this new behavior actually helps?
Please quantify how.
(As an aside, really not a fan of parse_path doing what you've
suggested.. will look closer once I have more justification to do so)
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