I'm having a major problem with my multipathing on my RHEL5 servers.
Here's the problem:
The paths to my SAN volume keep flip flopping between the two
controllers. Sometimes I see the path with the lowest priority set as
the 'active' path with the higher priority path set to 'enabled'.
Sometimes I see both paths set to 'enabled'. dmesg is contantly
outputting path error's and the SAN keep reporting error's about the
volume is not being managed by its preferred controller.
I had multipathing working great on our STK D280 SAN with brocade
switches but we've recently upgraded to the STK 6140 SAN with qlogic
5200 switches.
Here's my setup:
- RHEL5-64bit server
- stock qla2xxx hba driver
- device-mapper-multipath
- Single Qlogic QLE2460 HBA
- Sun's 6140 SAN
- Qlogic 5200 switch
My server has a single HBA connected to the switch which then connects
to each controller.
I've learned that for this hardware configuration, multipathing needs
AVT enabled so the fibre channel switch port for my server has its
'Host' type set to 'Sun with Veritas DMP'. My multipathing config is
using 'group_by_prio' for the path grouping policy.
Here's my multipath.conf:
blacklist
{
devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st|sda)[0-9]*"
}
defaults
{
udev_dir /dev
polling_interval 10
selector "round-robin 0"
path_grouping_policy group_by_prio
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_tpc /dev/%n"
path_checker tur
rr_min_io 100
rr_weight priorities
failback manual
no_path_retry fail
user_friendly_name yes
}
devnode_blacklist
{
devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st|sda)[0-9]*"
devnode "^hd[a-z][0-9]*"
devnode "^cciss!c[0-9]d[0-9]*"
}
devices
{
device
{
vendor "SUN"
product "CSM200_R" # the 6140 reports
that it's a CSM200_R
path_grouping_policy group_by_prio
path_checker tur
prio_callout "/sbin/mpath_prio_tpc /dev/%n"
getuid_callout "/sbin/scsi_id -g -u -s
/block/%n"
}
}
Here's some different output from the multipath command showing the
different states of my paths:
[root@plxp02log etc]# multipath -v2 -ll
mdi_logging (3600a0b800029a482000005d34695182b) dm-8 SUN,CSM200_R
[size=100G][features=0][hwhandler=0]
\_ round-robin 0 [prio=3][enabled]
\_ 1:0:0:1 sdc 8:32 [active][ready]
\_ round-robin 0 [prio=0][enabled]
\_ 1:0:1:1 sdf 8:80 [active][ready]
mdi_logging (3600a0b800029a482000005d34695182b) dm-8 SUN,CSM200_R
[size=100G][features=0][hwhandler=0]
\_ round-robin 0 [prio=3][enabled]
\_ 1:0:1:1 sdf 8:80 [active][ready]
\_ round-robin 0 [prio=0][active]
\_ 1:0:0:1 sdc 8:32 [active][ready]
dmesg output looks like this:
device-mapper: multipath: Failing path 8:32.
device-mapper: multipath: Failing path 8:80.
It looks like the path checker keeps failing and/or the priority of each
path keeps switching.
I don't know much anything about configuring san's or fibre channel
switches. I've only started learning the in's and out's of setting up
multipathing and so I don't really know how to troubleshoot this
problem. Is my multipathing config correct for this hardware?
Like I said before, it was working great on a D280 with a brocade
switch. I don't have access to the SAN gear and my SAN guy is pointing
the finger at my server config.
If someone could validate my config, tell what I'm doing right and what
I'm doing wrong, I'd be forever grateful. I've not found much info
online pertaining to this hardware config.
thanks,
James Fillman
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