topic Re: msa 2050 active/active setup on RHEL 6 in Operating System - Linux

msa 2050 active/active setup on RHEL 6

t. koenig — Mon, 16 Apr 2018 11:54:12 GMT

Hello,

I try to use my 2050 with 4 paths connected to the host as active/active array (2 dual-port HBA) . I use the Linux own dm-multipath solution, but it seems that whatever I do, it's running as round-robbin with only one path active at the same time.

I couldn't find any best practices about this so I hope here for help.

regards
Thomas

Re: msa 2050 active/active setup on RHEL 6

Torsten. — Mon, 16 Apr 2018 11:59:19 GMT

Not exactly sure about your configuration, but keep in mind the MSA works with ALUA, this means the server always talks to the owner controller of a LUN, not to the "non-optimized" partner "standby" controller.

Re: msa 2050 active/active setup on RHEL 6

t. koenig — Mon, 16 Apr 2018 15:59:31 GMT

I've two paths to controller A and two paths to B.

A Pool has the LUN so I woul like to have at least two active connections, to A and not only one?!

/etc/multipath.conf:
# multipath.conf written by anaconda

defaults {
        user_friendly_names yes
}
blacklist {
        devnode "^(ram|raw|loop|fd|md|dm-|sr|scd|st)[0-9]*"
        devnode "^hd[a-z]"
        devnode "^dcssblk[0-9]*"
        device {
                vendor "DGC"
                product "LUNZ"
        }
        device {
                vendor "IBM"
                product "S/390.*"
        }
        # don't count normal SATA devices as multipaths
        device {
                vendor  "ATA"
        }
        # don't count 3ware devices as multipaths
        device {
                vendor  "3ware"
        }
        device {
                vendor  "AMCC"
        }
        # nor highpoint devices
        device {
                vendor  "HPT"
        }
        wwid "3600508b1001c7726779870a9ed37a52d"
        wwid "*"
}
blacklist_exceptions {
        wwid "3600c0ff000293bdcb246d05a01000000"
}
multipaths {
        multipath {
                uid 0
                gid 0
                wwid "3600c0ff000293bdcb246d05a01000000"
                mode 0600
        }
}

multipath -ll
mpathb (3600c0ff000293bdcb246d05a01000000) dm-2 HPE,MSA 2050 SAN
size=4.4T features='0' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=1 status=active
| `- 1:0:0:0 sdb 8:16 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 3:0:0:0 sdd 8:48 active ready running
|-+- policy='round-robin 0' prio=1 status=enabled
| `- 2:0:0:0 sdc 8:32 active ready running
`-+- policy='round-robin 0' prio=1 status=enabled
  `- 4:0:0:0 sde 8:64 active ready running

Re: msa 2050 active/active setup on RHEL 6

Torsten. — Mon, 16 Apr 2018 16:00:48 GMT

>> A Pool has the LUN so I woul like to have at least two active connections, to A and not only one?!

This would be correct.

Re: msa 2050 active/active setup on RHEL 6

t. koenig — Mon, 16 Apr 2018 16:07:23 GMT

@Torsten. wrote:

This would be correct.

and that is my my problem - only one path is active!

Re: msa 2050 active/active setup on RHEL 6

Torsten. — Mon, 16 Apr 2018 16:17:01 GMT

You should probably have a device specific section in your multipath.conf,

Re: msa 2050 active/active setup on RHEL 6

t. koenig — Mon, 16 Apr 2018 16:25:58 GMT

yes, thats why I'm posting here my question.

Re: msa 2050 active/active setup on RHEL 6

Torsten. — Mon, 16 Apr 2018 16:28:15 GMT

This may help:

https://support.hpe.com/hpsc/doc/public/display?docId=emr_na-c01388344

basically the MSA2000 config applies.

Re: msa 2050 active/active setup on RHEL 6

simplylinuxfaq — Mon, 14 May 2018 08:31:56 GMT

It has used the default path selector which is "round-robin" unless modified in the configuration file. You could add 'path_selector' to the one that you wanted to be into defaults section and then reload the configs. Before the changes check with your vendor to see the supportablity and best practice to get this done, any precautions to be taken before reloading teh config changes.

Re: msa 2050 active/active setup on RHEL 6

t. koenig — Mon, 14 May 2018 09:29:44 GMT

Finally I changed my multipath.con defaults to:

defaults {
            user_friendly_names yes
            polling_interval           10
            path_selector              "round-robin 0"
            path_grouping_policy       group_by_prio
            prio                       alua   
            path_checker               tur    
            rr_min_io_rq               100
            flush_on_last_del          no
            max_fds                    "max"
            rr_weight                  uniform   
            failback                   immediate
            no_path_retry              18    
            queue_without_daemon       no
}

which make the grouping of my paths:

multipath -ll
mpathn (3600c0ff0003b6910cb0f9d5a01000000) dm-2 HPE,MSA 2050 SAN
size=4.3T features='1 queue_if_no_path' hwhandler='0' wp=rw
|-+- policy='round-robin 0' prio=50 status=active
| |- 1:0:0:0 sdb 8:16 active ready running
| `- 3:0:0:0 sdd 8:48 active ready running
`-+- policy='round-robin 0' prio=10 status=enabled
  |- 2:0:0:0 sdc 8:32 active ready running
  `- 4:0:0:0 sde 8:64 active ready running

Performance seems to be fine now.

Re: msa 2050 active/active setup on RHEL 6

nour_32 — Mon, 21 Oct 2019 05:03:24 GMT

could you please share the file /etc/multipath.conf here