Hello, 

I'm configuring an hypervisor for iSCSI Dell PS Series

It is a CentOS 7.3 + updates server.

The server has been already added to oVirt as a node, but without any storage domain configured yet.

It has access to one lun that will become the storage domain one.

Default oVirt generated multipath.conf is like this:

defaults {

    polling_interval            5

    no_path_retry               fail

    user_friendly_names         no

    flush_on_last_del           yes

    fast_io_fail_tmo            5

    dev_loss_tmo                30

    max_fds                     4096

}

devices {

    device {

        # These settings overrides built-in devices settings. It does not apply

        # to devices without built-in settings (these use the settings in the

        # "defaults" section), or to devices defined in the "devices" section.

        # Note: This is not available yet on Fedora 21. For more info see

        # https://bugzilla.redhat.com/1253799

        all_devs                yes

        no_path_retry           fail

    }

}

Apparently in device-mapper-multipath there is no builtin for this combination

  Vendor: EQLOGIC  Model: 100E-00          Rev: 8.1 

So, with the oVirt provided configuration a "show config" for multipath reports something like this at the end: 

        polling_interval 5

        path_selector "service-time 0"

        path_grouping_policy "failover"

        path_checker "directio"

        rr_min_io_rq 1

        max_fds 4096

        rr_weight "uniform"

        failback "manual"

        features "0"

and multipath layout this way

[root@ov300 etc]# multipath -l

364817197b5dfd0e5538d959702249b1c dm-3 EQLOGIC ,100E-00         

size=1.0T features='0' hwhandler='0' wp=rw

|-+- policy='service-time 0' prio=0 status=active

| `- 7:0:0:0 sde 8:64 active undef  running

`-+- policy='service-time 0' prio=0 status=enabled

  `- 8:0:0:0 sdf 8:80 active undef  running

[root@ov300 etc]# 

Following recommendations from Dell here:

http://en.community.dell.com/techcenter/extras/m/white_papers/20442422

I should put into defaults section these directives:

defaults {

    polling_interval            10

    path_selector               "round-robin 0"

    path_grouping_policy        multibus

    path_checker                tur

    rr_min_io_rq                10

    max_fds                     8192

    rr_weight                   priorities

    failback                    immediate

    features                    0

}

I'm trying to mix EQL and oVirt reccomendations to have the best for my use 

and arrived at this config (plus a blacklist section with my internal hd and my flash wwids that is not relevant here):

# VDSM REVISION 1.3

# VDSM PRIVATE

defaults {

    polling_interval            5

    no_path_retry               fail

    user_friendly_names         no

    flush_on_last_del           yes

    fast_io_fail_tmo            5

    dev_loss_tmo                30

#    Default oVirt value overwritten

#    max_fds                     4096

#

    max_fds                     8192

}

devices {

    device {

        # These settings overrides built-in devices settings. It does not apply

        # to devices without built-in settings (these use the settings in the

        # "defaults" section), or to devices defined in the "devices" section.

        # Note: This is not available yet on Fedora 21. For more info see

        # https://bugzilla.redhat.com/1253799

        all_devs                yes

        no_path_retry           fail

    }

    device {

        vendor                  "EQLOGIC"

        product                 "100E-00"

#        Default EQL configuration overwritten by oVirt default

#        polling_interval        10

#

        path_selector           "round-robin 0"

        path_grouping_policy    multibus

        path_checker            tur

        rr_min_io_rq            10

        rr_weight               priorities

        failback                immediate

        features                "0"

    }

}

After activating this config I have this mutipath layout

[root@ov300 etc]# multipath -l

364817197b5dfd0e5538d959702249b1c dm-3 EQLOGIC ,100E-00         

size=1.0T features='0' hwhandler='0' wp=rw

`-+- policy='round-robin 0' prio=0 status=active

  |- 7:0:0:0 sde 8:64 active undef  running

  `- 8:0:0:0 sdf 8:80 active undef  running

[root@ov300 etc]# 

NOTE: at this moment the storage is not yet configured as a storage domain.

I also changed /etc/iscsi/iscsd.conf and sysctl.d parameters as from EQL doc indications

From an iSCSI initiator point of view:

[root@ov300 ~]# iscsiadm -m session

tcp: [1] 10.10.100.9:3260,1 iqn.2001-05.com.equallogic:4-771816-e5d0dfb59-1c9b240297958d53-ovsd3910 (non-flash)

tcp: [2] 10.10.100.9:3260,1 iqn.2001-05.com.equallogic:4-771816-e5d0dfb59-1c9b240297958d53-ovsd3910 (non-flash)

[root@ov300 ~]# 

[root@ov300 ~]# iscsiadm -m session -P 1

Target: iqn.2001-05.com.equallogic:4-771816-e5d0dfb59-1c9b240297958d53-ovsd3910 (non-flash)

Current Portal: 10.10.100.41:3260,1

Persistent Portal: 10.10.100.9:3260,1

**********

Interface:

**********

Iface Name: ip1p1

Iface Transport: tcp

Iface Initiatorname: iqn.1994-05.com.redhat:f2d7fc1e2fc

Iface IPaddress: 10.10.100.87

Iface HWaddress: <empty>

Iface Netdev: <empty>

SID: 1

iSCSI Connection State: LOGGED IN

iSCSI Session State: LOGGED_IN

Internal iscsid Session State: NO CHANGE

Current Portal: 10.10.100.42:3260,1

Persistent Portal: 10.10.100.9:3260,1

**********

Interface:

**********

Iface Name: ip1p2

Iface Transport: tcp

Iface Initiatorname: iqn.1994-05.com.redhat:f2d7fc1e2fc

Iface IPaddress: 10.10.100.87

Iface HWaddress: <empty>

Iface Netdev: <empty>

SID: 2

iSCSI Connection State: LOGGED IN

iSCSI Session State: LOGGED_IN

Internal iscsid Session State: NO CHANGE

[root@ov300 ~]# 

Do you think it is ok?

Thanks for any comments,

Gianluca

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