Too many paths from multipath?

Too many paths from multipath?

[Jose Nuno Neto]

Hi

I'm setting up and testing multipath on a RedHat 5.3, 
device-mapper-multipath-0.4.7-23.el5
I have 2 HBAs connected to one LUN on a Hitachi Storage. Only two 
connections have been zoned
And that appears on sys fc_remote_ports information, but on multipath I 
see 4paths per HBA
I'm a little puzzled with this can you explain why? The Fabric we're 
using has several switch, could be this the reason?
Any hints on this are welcomed
Thanks
Jose



Info:

systool -c fc_remote_ports -v

Class = "fc_remote_ports"

Class Device = "0-0"
Class Device path = "/sys/class/fc_remote_ports/rport-3:0-0"
dev_loss_tmo = "30"
fast_io_fail_tmo = "off"
node_name = "0x50060e8004f3ca72"
port_id = "0x2a1f00"
port_name = "0x50060e8004f3ca72"
port_state = "Online"
roles = "FCP Target"
scsi_target_id = "0"
supported_classes = "Class 3"
uevent = <store method only>

Device = "rport-3:0-0"
Device path = 
"/sys/devices/pci0000:00/0000:00:02.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:05:00.0/host3/rport-3:0-0"
uevent = <store method only>


Class Device = "0-0"
Class Device path = "/sys/class/fc_remote_ports/rport-5:0-0"
dev_loss_tmo = "30"
fast_io_fail_tmo = "off"
node_name = "0x50060e8004f3ca62"
port_id = "0x201f00"
port_name = "0x50060e8004f3ca62"
port_state = "Online"
roles = "FCP Target"
scsi_target_id = "0"
supported_classes = "Class 3"
uevent = <store method only>

Device = "rport-5:0-0"
Device path = 
"/sys/devices/pci0000:00/0000:00:04.0/0000:0d:00.0/0000:0e:02.0/0000:0f:00.0/host5/rport-5:0-0"
uevent = <store method only>

####################################

multipath -ll
mpath1 (360060e8004f3ca000000f3ca00000066) dm-8 HITACHI,OPEN-V -SU
[size=26G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=4][active]
\_ 3:0:0:1 sdk 8:160 [active][ready]
\_ 3:0:0:16385 sdl 8:176 [active][ready]
\_ 3:0:0:32769 sdm 8:192 [active][ready]
\_ 3:0:0:49153 sdo 8:224 [active][ready]
\_ round-robin 0 [prio=4][enabled]
\_ 5:0:0:1 sdn 8:208 [active][ready]
\_ 5:0:0:16385 sdp 8:240 [active][ready]
\_ 5:0:0:32769 sdq 65:0 [active][ready]
\_ 5:0:0:49153 sdr 65:16 [active][ready]
mpath0 (360060e8004f3ca000000f3ca0000017d) dm-7 HITACHI,OPEN-V*3 -SU
[size=79G][features=1 queue_if_no_path][hwhandler=0][rw]
\_ round-robin 0 [prio=4][active]
\_ 3:0:0:0 sdc 8:32 [active][ready]
\_ 3:0:0:16384 sde 8:64 [active][ready]
\_ 3:0:0:32768 sdg 8:96 [active][ready]
\_ 3:0:0:49152 sdi 8:128 [active][ready]
\_ round-robin 0 [prio=4][enabled]
\_ 5:0:0:0 sdd 8:48 [active][ready]
\_ 5:0:0:16384 sdf 8:80 [active][ready]
\_ 5:0:0:32768 sdh 8:112 [active][ready]
\_ 5:0:0:49152 sdj 8:144 [active][ready]


####################################

systool -c fc_host -v host3
Class = "fc_host"

Class Device = "host3"
Class Device path = "/sys/class/fc_host/host3"
fabric_name = "0x1000006069909274"
issue_lip = <store method only>
node_name = "0x2000001b3214cfc7"
port_id = "0x2a1100"
port_name = "0x2100001b3214cfc7"
port_state = "Online"
port_type = "NPort (fabric via point-to-point)"
speed = "2 Gbit"
supported_classes = "Class 3"
symbolic_name = "QEM3472 FW:v4.04.05 DVR:v8.02.00.06.05.03-k"
system_hostname = ""
tgtid_bind_type = "wwpn (World Wide Port Name)"
uevent = <store method only>

Device = "host3"
Device path = 
"/sys/devices/pci0000:00/0000:00:02.0/0000:01:00.0/0000:02:00.0/0000:03:00.0/0000:04:02.0/0000:05:00.0/host3"
ct =
els =
fw_dump =
nvram = "ISP "
optrom_ctl = <store method only>
optrom =
sfp = ""
uevent = <store method only>
vpd = "‚r"
systool -c fc_host -v host5
Class = "fc_host"

Class Device = "host5"
Class Device path = "/sys/class/fc_host/host5"
fabric_name = "0x10000060699093ae"
issue_lip = <store method only>
node_name = "0x2000001b3281eb3f"
port_id = "0x201100"
port_name = "0x2100001b3281eb3f"
port_state = "Online"
port_type = "NPort (fabric via point-to-point)"
speed = "2 Gbit"
supported_classes = "Class 3"
symbolic_name = "QEM3472 FW:v4.04.05 DVR:v8.02.00.06.05.03-k"
system_hostname = ""
tgtid_bind_type = "wwpn (World Wide Port Name)"
uevent = <store method only>

Device = "host5"
Device path = 
"/sys/devices/pci0000:00/0000:00:04.0/0000:0d:00.0/0000:0e:02.0/0000:0f:00.0/host5"
ct =
els =
fw_dump =
nvram = "ISP "
optrom_ctl = <store method only>
optrom =
sfp = ""
uevent = <store method only>
vpd = "‚r"



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Re: Too many paths from multipath?

[Jakov Sosic]

On Wed, 2009-12-02 at 16:45 +0100, Jose Nuno Neto wrote:

> I have 2 HBAs connected to one LUN on a Hitachi Storage. Only two 
> connections have been zoned

If one connection goes to one switch, and that switch is connected to
two controllers on the storage, then you'll see two paths on that HBA in
your host. If you have two HBA's and second is connected to second
switch, which is also connected to two controllers of the stroage, then
you'll see 4 of them.

That is the situation in my company. It goes like this:


             ________Hitachi controller0
            /
HOST----switch0
            \
             \_______Hitachi controller1





-- 
|    Jakov Sosic    |    ICQ: 28410271    |   PGP: 0x965CAE2D   |
=================================================================
|                                                               |

Re: Too many paths from multipath?

[Jose Nuno Neto]

Ok that seems right, but on my case I have 4connections per HBA total of 
8per Lun

The info I got regarding zoning is that each HBA is connected/zoned to 
only one Storage controller
So that would make 2connections per Lun

What I suspect is that the Fabric here is made of 4switchs and that 
makes 4x plus. The SAN people just configured it with a generic "big" 
fabric zoning just one connection. but Linux shoes 4. could this be the 
reason?

Jakov Sosic wrote:
> On Wed, 2009-12-02 at 16:45 +0100, Jose Nuno Neto wrote:
>
>   
>> I have 2 HBAs connected to one LUN on a Hitachi Storage. Only two 
>> connections have been zoned
>>     
>
> If one connection goes to one switch, and that switch is connected to
> two controllers on the storage, then you'll see two paths on that HBA in
> your host. If you have two HBA's and second is connected to second
> switch, which is also connected to two controllers of the stroage, then
> you'll see 4 of them.
>
> That is the situation in my company. It goes like this:
>
>
>              ________Hitachi controller0
>             /
> HOST----switch0
>             \
>              \_______Hitachi controller1
>
>
>
>
>
>   

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informes que vous l'avez recu par erreur et que toute utilisation en est 
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Banque Europeenne d'Investissement.

The information in this message and/or attachments is intended solely for 
the attention and use of the named addressee and may be confidential. If 
you are not the intended recipient, you are hereby notified that you have 
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such a case please delete this message and kindly notify the European 
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Re: Too many paths from multipath?

[Edward Choi]

[-- Attachment #1.1: Type: text/plain, Size: 796 bytes --]

On Thu, Dec 3, 2009 at 1:57 AM, Jose Nuno Neto <j.neto@eib.org> wrote:

> Ok that seems right, but on my case I have 4connections per HBA total of
> 8per Lun
>
> The info I got regarding zoning is that each HBA is connected/zoned to only
> one Storage controller
> So that would make 2connections per Lun
>
> What I suspect is that the Fabric here is made of 4switchs and that makes
> 4x plus. The SAN people just configured it with a generic "big" fabric
> zoning just one connection. but Linux shoes 4. could this be the reason?
>
>
The number of paths shown on multipath -ll depends on how your zoning is
done. The easiest way is to check with your SAN administrator on how the
zoning is done and on how many switches and that will explain the 8 paths
you're seeing.

--
Regards,
Edward Choi.

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