[dm-devel] path priorities on Sun's 6140

James Fillman JFillman at cucbc.com
Mon Sep 17 18:36:32 UTC 2007


Ok. So I just realized that if I want to try the new RDAC support, then
I have to install the new beta kernel as well. It includes the RDAC
hardware handler.

I'm under serious pressure to get my cluster up and running asap and I
don't think I want to be installing a bunch of beta packages onto my
production servers. Especially kernels.

So this might mean not exploring the RDAC solution. Redhat's docs say
that they support a Sun OpenStorage D280 and our Sun rep says the 6140
is essentially identical. If that's the case, what am I don't wrong?

cheers,
--james

-----Original Message-----
From: dm-devel-bounces at redhat.com [mailto:dm-devel-bounces at redhat.com]
On Behalf Of James Fillman
Sent: Monday, September 17, 2007 11:18 AM
To: device-mapper development
Subject: RE: [dm-devel] path priorities on Sun's 6140

Thanks for getting back to me Tore, Hannes, and Eckebrecht.

I've downloaded and installed the latest device-mapper-multipath rpm
from Redhat. It's still only beta but I figured I give it a try. I see
that there's an rdac checker in there but I don't see a hardware
handler.

Is anyone running RHEL against a Sun 6140 SAN? Trying to get a
definitive answer from Redhat on their support for this SAN has been
impossible. The mailing list hasn't been too helpful either.

If RDAC is the way to go
  1. do I need to use a hardware handler? There doesn't seem to be one
in their latest RPM.
  2. What Host type do I chose on the SAN?
  3. What should the path grouping policy by? Tore: you mentioned using
group_by_serial
  4. What should the path checker be?

I'm going to take a stab at it and guess this, can anyone confirm?:
/etc/multipath.conf

defaults
{
        udev_dir                /dev
        polling_interval        10
        selector                "round-robin 0"
        path_grouping_policy    group_by_serial
        getuid_callout          "/sbin/scsi_id -g -u -s /block/%n"
        prio_callout            "/sbin/mpath_prio_rdac /dev/%n"
        path_checker            tur
        rr_min_io               100
        rr_weight               uniform
        failback                immediate
        no_path_retry           queue
        user_friendly_name      yes
}
devices
{
        device
        {
                vendor                  "SUN"
                product                 "CSM200_R"
                path_grouping_policy    group_by_prio
                path_checker            tur
                prio_callout            "/sbin/mpath_prio_rdac /dev/%n"
                getuid_callout          "/sbin/scsi_id -g -u -s
/block/%n"
                rr_weight               uniform
                rr_min_io               1000
                features                "1 queue_if_no_path"
        }
}

cheers,
--james


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