[dm-devel] RHEL5 and RDAC/Multipath

Nuno Fernandes npf-mlists at eurotux.com
Mon Sep 24 13:39:12 UTC 2007


Hi,

We've bought and IBM BladecenterH and IBM DS4700 storage.
We are using Redhat Enterprise Linux 5 and we are trying to put multipath 
working.

RHEL5 we are using uses 2.6.18-8.1.3.el5xen. We've ported rdac patch 
(http://kernel.org/pub/linux/kernel/people/agk/patches/2.6/2.6.21/dm-mpath-rdac.patch) 
to RHEL5 kernel. We've also updated multipath-tools to support 
mpath_prio_rdac.

Our multipath.conf is:

devnode_blacklist {
        devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
        devnode "^hd[a-z]"
        devnode "^cciss!c[0-9]d[0-9]*"
        #USB 4G Flash drive inside HS21
        devnode "sda" 
}

defaults {
        multipath_tool  "/sbin/multipath -v0"
        udev_dir        /dev
        polling_interval 5
        default_selector        "round-robin 0"
        default_getuid_callout  "/sbin/scsi_id -g -u -s /block/%n"
        #default_prio_callout    "/bin/true"
        failback                immediate
        path_checker            rdac
        hardware_handler        "1 rdac"
        prio_callout            "/sbin/mpath_prio_tpc /dev/%n"
        path_grouping_policy    group_by_prio
}

multipaths {
        multipath {
                wwid                    3600a0b8000320bea0000048f46e52137
                alias                   client_data
        }
}

When we start multipath -v2 it creates multipath devices. I can see 2 active 
paths (active controler) and 2 ghost paths (standby controler).
When i unplug 2 active fibre that connect the fabric to DS4700, multipath 
reports I/O errors and doesn't failover the controler.

Any ideas?

Thanks for any help
Nuno Fernandes




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