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ISCSI multipathing Ubuntu to MSA2313i

Posted on 2014-02-05
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Last Modified: 2014-02-21
Hello.

I want to loadbalancing a ISCSI connection against my MSA2312i ISCSI SAN that is SCSI-3 ALUA

My problem is that all my traffic is going over one interface,

Is there anyone now how I should write my multipath.conf to make my roundrobin loadbalancing work..

(I got it work once but i dont really know how i did.)

all traffic is on the same LAN but separated by static routes.

trunkated routing table:
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
xx
xx
101.150.1.101   0.0.0.0         255.255.255.255 UH        0 0          0 eth3
101.150.1.102   0.0.0.0         255.255.255.255 UH        0 0          0 eth5
101.150.1.103   0.0.0.0         255.255.255.255 UH        0 0          0 eth3
101.150.1.104   0.0.0.0         255.255.255.255 UH        0 0          0 eth5



multipath -ll
data (3600c0ff00011dfd55a24e95201000000) dm-1 HP,MSA2312i
size=7.3T features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=130 status=active
| |- 6:0:0:1 sde 8:64 active ready running
| `- 4:0:0:1 sdd 8:48 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
  |- 3:0:0:1 sdb 8:16 active ready running
  `- 5:0:0:1 sdc 8:32 active ready running
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Question by:Daniel-San
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LVL 21

Assisted Solution

by:Mazdajai
Mazdajai earned 250 total points
ID: 39846415
You have different path priority (10 and 130) which appears to be the issue.

Do you have prio option set to const in your multipath.conf? (grep prio /etc/multipath.conf)
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Assisted Solution

by:Sandy
Sandy earned 250 total points
ID: 39855527
yes, priority must be same

TY/SA
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Author Comment

by:Daniel-San
ID: 39867194
Thanx for you Answers!

No I have multiple prio options in my config, I wish to clean up this config file, but I dont really now what options I DO need and what I dont need. I only have the MSA connected.

Can you guys please advise?

cat /etc/multipath.conf
      defaults {
                udev_dir              /dev
                polling_interval      10
                path_selector         "round-robin 0"
                path_grouping_policy  multibus
                getuid_callout        "/lib/udev/scsi_id --whitelisted --device=/dev/%n"
                prio                  alua
                path_checker          readsector0
                rr_min_io             100
                max_fds               8192
                rr_weight             priorities
                failback              immediate
                no_path_retry         fail
                user_friendly_names   yes
      }                  
      
      blacklist {
                # Blacklist by WWID
                wwid "*"

          # Blacklist by device name
             devnode "^sda"
      }

       blacklist_exceptions {
              wwid "3600c0ff00011dfd55a24e95201000000"
      }

      multipaths {
               multipath {
                 wwid 3600c0ff00011dfd55a24e95201000000
                 alias data
         }
}
      device {
            vendor "HP"
            product "MSA2312fc|MSA2324fc|MSA2312i|MSA2324i|MSA2000s VOLUME"
            path_grouping_policy group_by_prio
            getuid_callout "/sbin/scsi_id -g -u -s /block/%n"
            path_selector "round-robin 0"
            path_checker tur
            features "0"
            hardware_handler "0"
            prio_callout "/sbin/mpath_prio_alua /dev/%n"
            failback immediate
            rr_weight uniform
            no_path_retry 18
            rr_min_io 100
      }

/Daniel
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LVL 13

Assisted Solution

by:Sandy
Sandy earned 250 total points
ID: 39867210
prio = const
prio_callout = /sbin/true

I would suggest to use this.

TY/SA
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LVL 21

Assisted Solution

by:Mazdajai
Mazdajai earned 250 total points
ID: 39872352
Change
prio = alua

Open in new window

to
prio = const

Open in new window


and reload multipathd:
service multipathd reload
multipath -ll

Open in new window

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Author Comment

by:Daniel-San
ID: 39873690
Ok, thx all for your answers! Appreciated!

Mazdajai, Is reload an online command? Or will I loose contact with volumes so I need to shut I/O down first?

Regards
Daniel
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LVL 21

Assisted Solution

by:Mazdajai
Mazdajai earned 250 total points
ID: 39873705
The reload argument means to re-read the multipath.conf.

There should be no downtime but it should be done off business hours if it is production.
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LVL 13

Accepted Solution

by:
Sandy earned 250 total points
ID: 39874051
reload won't effect running IO.

TY/SA
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Author Closing Comment

by:Daniel-San
ID: 39876119
Ok, Thank you guys!
/Daniel
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