Limitations associated with Direct Connecting arrays to UCS FIs.

[JAdams159]

I understand that in order to direct connect an array to UCS, the FIs have to be put into Switch mode(NPIV).  But once the FI's are in Switch Mode, is it impossible to attach other SAN switches to the fabric interconnects?

It is my understanding that you could accomplish this because it wouldn't be much different then an extended SAN fabric in which an array's traffic would have to travel through 2 FC switches to arrive at a host.  But perhaps I'm missing something.

Thanks in advance.

[Marcin Latosiewicz · Accepted solution]

You can have directly attached storage and FC switches at the same time, in fact until recently it was required since UCS did not do zoning. 

http://www.cisco.com/c/en/us/support/docs/servers-unified-computing/ucs-infrastructure-ucs-manager-software/116082-config-ucs-das-00.html

The questions is whether you really want to do it that way, I think for 95% of deployments, if not more, end host mode is recommended. 

If you're already planning to attach FC switches, best to place storage on them. 

Have a look at FlexPod (of Vblock) designs.

[Walter Dey]

In addition what Marcin said, you have to be aware of the following caveats

- Yes it is supported in FC Switch mode to connect arrays directly to FI and SAN

- However, you need 2 separate VSAN's, one for the direct attached Array, one for the SAN

- Only Cisco Switches (Nexus 5k, MDS) are supported, no Brocade

- FI in Switch mode only supports Basic zoning (no enhanced)

- FI in Switch mode doesn't Support static FC Domain id's

Walter.