[dm-devel] defining paths with DDN 8500
Mike White
homebrewmike at yahoo.com
Thu Sep 13 21:59:45 UTC 2007
Thanks Tore and Christophe. Unless someone has something for DDN, I'll have to roll my own (and share, of course.)
On a somewhat related note - do you know if there a concise description of the existing prio's - outside of what's in the /* */'s?
Thanks-
-Mike
----- Original Message ----
From: Tore Anderson <tore at linpro.no>
To: device-mapper development <dm-devel at redhat.com>
Sent: Thursday, September 13, 2007 3:33:11 AM
Subject: Re: [dm-devel] defining paths with DDN 8500
* Mike White
> I'm working with the multipathing package and a DDN 8500. I've been
> able to successfully configure failover and failback. The system is
> configured as such:
> qla_port_1 ---- ctrl A port 4 ---- LUN 3 (LUN 7)
> qla_port_2 ---- ctrl B port 4 ---- LUN 7 (LUN 3)
>
> Where LUN 3 is on a dedicated port to qla_port_1 and qla_port_2 is
> dedicated to LUN 7.
>
> The problem that I'm having is all the traffic is going through
> qla_port_1, qla_port_2 appears to be sitting idle until a failover.
>
> To compensate, I've been using dmsetup to force the qla_port_2 ----
> LUN 7 path.
>
> Is there a better way than using dmsetup to do this? multipath isn't
> an option, as it negatively impacts performance.
Sounds like you're in need of a prio_callout. I'm not familiar with
your hardware so I don't know if there's already one available, if not,
make a simple script that for example prints "2" for the paths you want
to prefer and "1" for the ones you want to use as backups. Then set
path_grouping_policy to "failover". You might also want to set
failback to "immediate".
Regards
--
Tore Anderson
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