[stgt] Multiple active paths

[Chandra Seetharaman]

Hi Mark,

dm multipath is treating multiple paths to the iSCSI lun as fail over
paths. Hence it is putting them in different path groups. It has nothing
to do with iSCSI target.

Add the following stanza to /etc/multipath.conf and restart multipath by
running "multipath -f billy" and "service multipathd restart"

------------------
devices {
	device {
               vendor "IET"
               product "VIRTUAL-DISK"
               path_grouping_policy multibus
        }
}
------------------

For more information on multipath usage, have a read at: http://sources.redhat.com/lvm2/wiki/MultipathUsageGuide

chandra

On Wed, 2010-06-02 at 15:23 +0200, Mark Ruys wrote:
> Hi,
> 
> I've just succesfully set up an tgtd target on a CentOS 5.5 machine 
> having four (non-bonded) nic's. My initiator connects as follows:
> 
> billy (1IET_00010001) dm-3 IET,VIRTUAL-DISK
> [size=400G][features=0][hwhandler=0][rw]
> \_ round-robin 0 [prio=1][active]
>   \_ 17:0:0:1  sdh  8:112  [active][ready]
> \_ round-robin 0 [prio=1][enabled]
>   \_ 19:0:0:1  sdo  8:224  [active][ready]
> \_ round-robin 0 [prio=1][enabled]
>   \_ 20:0:0:1  sdz  65:144 [active][ready]
> \_ round-robin 0 [prio=1][enabled]
>   \_ 18:0:0:1  sdj  8:144  [active][ready]
> 
> So the path through /dev/sdh is active and used. For another EMC target, 
> I get:
> 
> bulbby (360060160b9781b008488bd4f0e2fde11) dm-7 DGC,RAID 10
> [size=15G][features=1 queue_if_no_path][hwhandler=1 emc][rw]
> \_ round-robin 0 [prio=2][active]
>   \_ 14:0:0:5  sdr  65:16  [active][ready]
>   \_ 16:0:0:5  sdy  65:128 [active][ready]
> \_ round-robin 0 [prio=0][enabled]
>   \_ 13:0:0:5  sdaq 66:160 [active][ready]
>   \_ 15:0:0:5  sdar 66:176 [active][ready]
> 
> As I understand it, in this case both /dev/sdr and /dev/sdy are used 
> doubling the network throuhgput capacity. How can I achieve this with 
> tgtd? I tried to find an answer in this mailing list in vain.
> 
> Thanks,
> 
> Mark
> 
> /etc/tgt/targets.conf:
> 
> default-driver iscsi
> 
> <target iqn.2010-05.net.maas:rijn.tgt>
>          backing-store /dev/VG00/Billy
>          initiator-address 192.168.91.0/24
>          initiator-address 192.168.92.0/24
> </target>
> 
> 

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