The documentation that you're seeing for CDOT which refers to a cluster interconnect (switchless cluster) with 10GbE cables from e0a <-> e0a and e0b <-> e0b is actually the cluster management network, which is something altogether different from HA. The cluster management network/interconnect is used for intra-cluster operations such as non-disruptive volume moves.

The HA connection in either case (7-Mode/CDOT) is handled over a backplane connection with the 80x0 series of controllers, this connection keeps the NVRAM of the controllers in sync with one another in the event of a catastrophic event on one controller or another.

The important thing to note here is that when you're talking about a high availability pair of controllers, going forward you'd refer to them as an HA pair. When you're talking about a cluster, going forward that will be taken to mean 2+ systems, whether linked with HA or not, that are participating in a Clustered Data ONTAP cluster. Understandably it is a bit confusing since we've all grown accustomed to the old definition of a cluster under 7-Mode.

Hopefully you'll be able to take this opportunity with your hardware upgrade to transition to CDOT. Once you've gotten past the migration hurdle, it's a really wonderful storage OS and you'll be amazed at some of the things you can do with it and wonder how you got along without them before. There are so many cool features like non-disruptive volume moves, rolling upgrades, single-namespace for NAS, true multi-tenancy -- the list goes on and on and even more enhancements are on the horizon.

Anthony Bar
tbar@berkcom.com
Berkeley Communications

On Oct 5, 2015, at 1:41 PM, Paul Letta <letta@jlab.org> wrote:

Hello,

I've currently got a FAS3240 HA pair (with each controller in its own chassis). I am swapping the heads with a FAS8020 HA pair. This is 7-mode 8.2.x.

With the current 3240's..there are a cluster interconnects that runs between c0a and c0b on both controllers.

The new 8020 is a HA pair in one chassis. Are cluster interconnects required ?

The Installation and Setup Instructions guide shows it differently for cDOT and 7-mode..

For cDOT is says to connect e0a to e0a and e0b to e0b for the cluster interconnect.

This is listed as a "switchless cluster" for cDOT. (no mention of 7-mode here)

For 7-mode and cDot for a "switched HA configuration", it has e0a and e0b for both heads going the upstream switches.

The guide I'm talking about is at:

library.netapp.com/ecm/ecm_download_file/ECMP1199906

Install Hardware (blue 2) step 2.2

I am not planning on using e0a or e0b for networking at all. The purchase did not come with any cables that will work between these ports.

Thanks.

Paul

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