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Re: msa 2050 active/active setup on RHEL 6

 
t. koenig
Occasional Contributor

msa 2050 active/active setup on RHEL 6

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
10 REPLIES 10
Torsten.
Acclaimed Contributor

Re: msa 2050 active/active setup on RHEL 6

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.


Hope this helps!
Regards
Torsten.

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t. koenig
Occasional Contributor

Re: msa 2050 active/active setup on RHEL 6

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

 

Torsten.
Acclaimed Contributor

Re: msa 2050 active/active setup on RHEL 6

>> 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.


Hope this helps!
Regards
Torsten.

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those who understand binary, and those who don't.

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t. koenig
Occasional Contributor

Re: msa 2050 active/active setup on RHEL 6


@Torsten. wrote:

 

This would be correct.


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

Torsten.
Acclaimed Contributor

Re: msa 2050 active/active setup on RHEL 6

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

 


Hope this helps!
Regards
Torsten.

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t. koenig
Occasional Contributor

Re: msa 2050 active/active setup on RHEL 6

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

Torsten.
Acclaimed Contributor

Re: msa 2050 active/active setup on RHEL 6

This may help:

 

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

 

basically the MSA2000 config applies.


Hope this helps!
Regards
Torsten.

__________________________________________________
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those who understand binary, and those who don't.

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simplylinuxfaq
Frequent Advisor

Re: msa 2050 active/active setup on RHEL 6

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. 

Thanks,
SimplyLinuxFAQ
t. koenig
Occasional Contributor

Re: msa 2050 active/active setup on RHEL 6

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.