I have an existing M1000e chassis partially populated with M600s and M610s.
I'm purchasing an additional M1000e chassis and a couple of blades so I have fault redundancy. I would love to be able to use any existing blades and any future blades in either chassis.
From what I've read and understood, it appears I can't use M710HD or M620 due to my existing fabric limitations - is that correct? It appears on the M620, your Fabric A choices are all dual port 10Gb and on the M710, the Fabric A choices are a Broadcom 5709 Quad Port 1GbE NIC
In my existing chassis
Fabric A is GigE with 4 Cisco Catalyst WS-CBS3130G-S swtiches
Fabric B is FC 4GB with 2 Brocade 4424 switches
Fabric C is GigE with 4 Cisco Catalyst WS-CBS3130G-S switches
This allows us redundancy on every link and each vSphere host is presented with 4x1GigE links and then 2x4GigFC links to the SAN
The M600 blades each have 2xGigE links on the embedded LOM, 2x4GigFC on a QME2472 mezzanine card,and 2xGigE on a Broadcom M5708t mezzanine card
The M610 blades each have 2xGigE links on the embedded LOM, 2x8GigFC on a QME2572 mezzanine card,and 2xGigE on a Broadcom M5709t mezzanine card
We're already replacing the Brocade 4424 switches with passthroughs to some MDX 8GB switches - this will allow the M600s to still connect to the SAN (though at 4GB) and the M610s to connect at 8GB.
Other random stuff to consider -
we want to stay with half height blades with no more than 12 total cores due to Oracle licensing requirements.
All blades run vSphere 4.1u2 or 5.0u1
Updated below is my current understanding of the Blades LOM/NDC + IO Module handshaking.
The M620 options for network daughter card (NDC) in Fabric A are 10Gb -k dual port NICs. They will run at the lowest common denominator (1Gb) with your current Cisco switches in Fabric A.
The M710HD can be used if you go with the Broadcom Quad-Port 5709 1-GbE as your LOM; but please note that you would be only able to use half the card's port b/c the Cisco Catalyst switch only has one internal port per mezz connection.
To complement Kong Yangs answer:
The M620 with QLogic® QMD8262-KR Dual-Port 10GbE NDC on Fabric A doesn't support 1GbE operation according to the Technical Guide so that leaves you to choose between Broadcom and Intel.