Multipathing issue

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Hi,

I have a strange problem with multipathing. I'm testing the multipathing behavior and I don't understand that issue.

# lsb_release -a
LSB Version: :base-4.0-amd64:base-4.0-noarch:core-4.0-amd64:core-4.0-noarch:graphics-4.0-amd64:graphics-4.0-noarch:printing-4.0-amd64:printing-4.0-noarch
Distributor ID: RedHatEnterpriseServer
Description: Red Hat Enterprise Linux Server release 6.4 (Santiago)
Release: 6.4
Codename: Santiago

# cat /etc/multipath.conf
defaults {
polling_interval 10
max_fds 8192
}

devices {
device {
vendor "3PARdata"
product "VV"
no_path_retry 18
features "0"
hardware_handler "0"
path_grouping_policy multibus
getuid_callout "/lib/udev/scsi_id --whitelisted --device=/dev/%n"
path_selector "round-robin 0"
rr_weight uniform
rr_min_io_rq 1
path_checker tur
failback immediate
}
}

My system attacks a SAN storage and I have presented 1 LUN through 2 HBA

# lspci|grep -i fibre
04:00.0 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)
04:00.1 Fibre Channel: QLogic Corp. ISP2532-based 8Gb Fibre Channel to PCI Express HBA (rev 02)

I see 4 paths and this is correct:

# multipath -ll
1mmpathb (350002ac00a5024ad) dm-0 3PARdata,VV0m
size=56G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
|- 1:0:0:0 sdd 8:48 active ready running
|- 1:0:1:0 sde 8:64 active ready running
|- 0:0:1:0 sdc 8:32 active ready running
`- 0:0:0:0 sdb 8:16 active ready running

When I disable the switch port of one of the HBA's, occurs logical thing:

# multipath -ll
1mmpathb (350002ac00a5024ad) dm-0 3PARdata,VV0m
size=56G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
|- 1:0:0:0 sdd 8:48 active ready running
|- 1:0:1:0 sde 8:64 active ready running
|- 0:0:0:0 sdb 8:16 failed faulty running
`- 0:0:1:0 sdc 8:32 failed faulty running

But then, and this is my problem, few seconds after, the paths disappear and I can't see its status:

# multipath -ll
1mmpathb (350002ac00a5024ad) dm-0 3PARdata,VV0m
size=56G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
|- 1:0:0:0 sdd 8:48 active ready running
`- 1:0:1:0 sde 8:64 active ready running

When I enable the switch port, all return to work fine:

# multipath -ll
1mmpathb (350002ac00a5024ad) dm-0 3PARdata,VV0m
size=56G features='1 queue_if_no_path' hwhandler='0' wp=rw
`-+- policy='round-robin 0' prio=1 status=active
|- 1:0:0:0 sdd 8:48 active ready running
|- 1:0:1:0 sde 8:64 active ready running
|- 0:0:0:0 sdb 8:16 active ready running
`- 0:0:1:0 sdc 8:32 active ready running

I think the multipath does not work correctly. multipath does not inform me that the paths disappeared. I want to know that the paths are failing and which ones.

I have to look syslog to find the error.

Does anybody know how I can do to don't loose the failed paths?

Thank you very much.

SW

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