Archive for October, 2011

IBM DS3500 Multipathing / vSphere MPIO


Below I’m summrizing how I have configured the IBM DS3500 SAN Storage for my DR Site.

Each SCSI port in the IBM DS3500 with different subnet,

  • Port-3 10.10.10.1
  • Port-4 10.10.20.1
  • Port-5 10.10.30.1
  • Port-6 10.10.40.1 /24

 

The Storage Processor Ports are connected to the Dell 2724 switches, 10.x subnet goes into Port-1 in pSwitch1 and subnet 20.x goes into pSwitch1 Port-2, Subnet 30.x goes into pSwitch2 into Port-1 and Subnet 40.x goes into pSwitch2 Port-2.

In the ESX side, one vSwitch attached to two vmnic’s vmnic2 and vmnic3. In this vSwitch  created four VMkernel Portgroups,

  • iSCSI-01 10.10.10.30
  • iSCSI-02 10.10.20.30
  • iSCSI-03 10.10.30.30
  • iSCSI-04 10.10.40.30

If all the nics are active at the same time and try to vmkping to the Storage Processor, (DUP!) Duplicate pings from one of the subnet, then the ping will stop working but it will work for the other Storage Processor.

To overcome this issue is to have the vmnic2 is active for iSCSI-01 and iSCSI-02 and vmnic3 unused for iSCSI-01 and iSCSI-02. The same for the other Portgroups, vmnic3 is Active only for iSCSI-03 and iSCSI-04 and vmnic2 is unused these two Portgroups. After that the ping is steady without (DUP!).

iSCSI Binding is done on the iSCSI adapter to have all the VMkernel Portgroups. esxcli swiscsi nic add -n -d vmk# vmhba33.

After that, all the four paths are appeared, and changed the Storage Path to Round Robin to have them all Active(I/O) at the same time.

Testing were done, by switching off pSwitch1 and connection were alive to the SAN Storage, and the number of paths changed from four to Two. Turned off pSwitch2 and the connection were alive too to the SAN Storage and the number of paths changed from four to two.

As per IBM, they say it’s not the recommended way of having this config and its unsupported  I don’t know the reason why it’s not supported / recommended. The only support method they say as per the IBM engineer who installed this SAN Storage is to have only two paths if only one Controller is installed and cannot put four connections!!! But he surprised of what he has seen from my configuration :). As per him, he said I can use the 8 Paths ONLY if the second controller is installed, which is logically I can’t find any answer for it why is that!!!!

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