Red Hat Multipathing Help
 

Hello,

I could use some help with device-mapper multipathing in conjunction with fdisk. I am more of a solaris expert and now trying to grasp linux (red hat).

I have a server that I plan to cluster (future assignment) which is attached to a Netapp SAN via emulex LPe11002 HBA. I have 8 paths to the LUN I created and I can see the multipath device (/dev/mapper/mpath1). Below is my multipath.conf file:

defaults
{
user_friendly_names yes
max_fds max
queue_without_daemon no
}
blacklist
{
wwid 36a4badb05303fc0013e05e2b475c9aed
wwid 36a4badb05303fc0013e0ba56156bca98
devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
devnode "^hd[a-z]"
devnode "^cciss!c[0-9]d[0-9]*[p[0-9]*]"
}
devices
{
device
{
vendor "NETAPP"
product "LUN"
getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
prio_callout "/sbin/mpath_prio_ontap /dev/%n"
features "1 queue_if_no_path"
hardware_handler "0"
path_grouping_policy group_by_prio
failback immediate
rr_weight uniform
rr_min_io 128
path_checker directio
flush_on_last_del yes
}
}
multipath {
wwid 360a98000486e5a704b6f596179324e6e
alias db
path_grouping_policy multipath
path_selector "round-robin 0"
failback immediate
}





Question 1:

When I look at fdisk -l, I can see all 8 paths to the same LUN. Although I partition /dev/mapper/mpath1, I can still see that 7 of the 8 still say "Disk /dev/sdX doesn't contain a valid partition table". I would think that all 8 would have this removed. I execute '/usr/sbin/lpfc/lun_scan all' and it doesn't work. I am looking to clean this up...what should I do? It seems weird to have to do it to all 8 paths!

Question 2:

Why does my alias, 'db' not show up under /dev/mappers?

Question 3:

Is there a way for fdisk -l to display one lun rather than displaying all 8 paths to the lun?


What is the standard procedure (commands) people execute when adding a new lun to a server with multipathing so it is nice and clean?

Thanks!

Well.. there a are lots of things to "fix" before something like this would work right (reads /proc/partitions, can contain dead dm's). So, I'm going to say "no". You can use multipath -l to see your multipath'd devices and then select the dm devices to peruse from there.

Hello Hooch ,

you must have 2 controller at the storage and 2 san s/w , so that the server sees a single disk thru 8 paths , please restrt your multipath daemon ,service multipathd restart.

Regards,

dhofar, not everything is multipath aware... nor should they be. There are a TON of variables and it is VERY hard to determine what every user is thinking or doing with regards to devices and paths.

So... no... at best you could write options into tools based on some kind of assumptions... but even so, it could get really ugly (talking about the assumptions).

Useful
 

Interesting information shared with useful and helpful ideas and good topic.