Date: Wed, 9 Nov 2005 13:25:34 -0800 From: Danny Howard <dannyman@toldme.com> To: freebsd-geom@freebsd.org, freebsd-hackers@freebsd.org Subject: GEOM for multipath? How? Message-ID: <20051109212534.GD72876@ratchet.nebcorp.com>
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Hello,
Alas, my fancy Engenio dual-FC disk array is inaccessible to me for
testing. :( But we are working on switching over to RHEL due to
availability of FC multi-path redundancy drivers for RHEL but nada for
FreeBSD.
I was reading Linux' md man page, which sounds awfully similar to geom,
and they have a provider called:
MUTIPATH
MULTIPATH is not really a RAID at all as there is only one real device
in a MULTIPATH md array. However there are multiple access points
(paths) to this device, and one of these paths might fail, so there
are some similarities.
A MULTIPATH array is composed of a number of logical different
devices, often fibre channel interfaces, that all refer the the same
real device. If one of these interfaces fails (e.g. due to cable prob-
lems), the multipath driver to attempt to redirect requests to another
interface.
And I says to myself "AHA! Multipath should be easy to implement on
FreeBSD as well, via geom." But I can't find an obvious way given
existing geom utils to do this. And like I said, the box I'd use this
on is inaccesible for now.
Basically, I'd want a provider, that would see two disks, and if it
could talk to one disk, it would, else it would talk to the other.
Anyone here have a multipath capable hardware infrastructure who could
test out some applicable geom config? Like I say a third time ... I
have a nice Engenio 2882 FC sitting in a Datacenter, 3,000 miles away,
that is connected to a system that is offline. I get to visit after
Thanksgiving ... :/
Thanks,
-danny
--
http://dannyman.toldme.com/
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