Ed La
2 Iron

CX3-10c SP Controller

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Dear,


I have the following FC Cabling in which there is ONLY 1 FC Uplink to each Fibre Switch.

I would like to confirm if a Fibre Switch is down, can the data be routed via internal Trepassing automatically to the other SP Controller ????  Thanks.


cx3-10c SP Controller.jpg

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anand2405
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Re: CX3-10c SP Controller

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If the B3 path fails, it will trigger a trespass event on the Storage, the Lun ownership will changed from SPB to SPA and the Lun will now be active through A3 and IOPS will be served.

Anand.

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Ed La
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Re: CX3-10c SP Controller

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My powermt shows that there are multipath to both controllers, but in fact, the LUN is currently owned by SP B.

So, does it mean that even if the path to SP B3 fail, the data can still be routed to SP B via internal trepassing from SP A automatically without manual intervention?

[root@ksgdb01 ~]# powermt display dev=emcpowerm
Pseudo name=emcpowerm
CLARiiON ID=CK200074900971 [ksgdb01]
Logical device ID=60060160FDE01E004034122D7F29E311 [LUN 3]
state=alive; policy=CLAROpt; queued-IOs=0
Owner: default=SP B, current=SP B       Array failover mode: 1
==============================================================================
--------------- Host ---------------   - Stor -  -- I/O Path --   -- Stats ---
###  HW Path               I/O Paths    Interf.  Mode     State   Q-IOs Errors
==============================================================================
   2 qla2xxx                sdam        SP B3    active   alive      0      0
   1 qla2xxx                sdah        SP A3    active   alive      0      0

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anand2405
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Re: CX3-10c SP Controller

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If the B3 path fails, it will trigger a trespass event on the Storage, the Lun ownership will changed from SPB to SPA and the Lun will now be active through A3 and IOPS will be served.

Anand.

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zhouzengchao
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Re: CX3-10c SP Controller

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As your current configuration, PowerPath will trigger a explicit trespass to switch the LUN ownership from SPB to SPA. To achieve the goal to redirect the I/O from SPA to SPB for processing, which means there is no explicit trespass, you must configure your array initiator failover mode to 4 (ALUA) and the PowerPath must also be set to ALUA mode.

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Ed La
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Re: CX3-10c SP Controller

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Since I have my LUN ownership distributed evenly to SP A and SP B, do you know if ALUA would introduce extra loading to the SP when data traffic is received through the non-optimal path?

It seems my CX3-10c EMC Navisphere Manager 6.24.2.5.0 Group Initiator Edit does not have the option 4 for ALUA:-

CX3-10c Group Edit Initiators.jpg

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zhouzengchao
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Re: CX3-10c SP Controller

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I remember that ALUA was first introduced in FLARE Release 26, you must upgrade FLARE to use ALUA.

If you use ALUA, the un-optimal path will of course lead to some delay because the I/O is now going through the CMI channel (PCI bus).  But the workload will be still under balance status as your design between SPA/SPB, because the i/o is still processed by it's current owner.