I am not sure if I can clearly explain my existing fabric but I will give a try
I have 24 Ports on each Blade Switch (Native Mode) which are used as below :
16 Ports to ESX Hosts
4 Ports to Hitachi
1 Port to HP EVA
1 Port to HP P2000
2 Ports to two servers
We don't have seperate fabric. We don't have a room to scale out now !!!
We have 4 unused 7800 Switches, I would like to use them..... Could any one suggest on the best way to use them as seperate fabric ??
My plan A is to convert the mode of balde switch to AG and connect each switch to 7800 as below :
4 NPIV ports to 7800
Leave 4 Ports to Hitachi as it is ( I am not sure if it supported in AG Mode)
On 7800 Switch
4 Ports from Blade Switch Ports (NPIV)
2 Ports from HDS
2 Ports from 7800 to HP EVA
2 Ports from 7800 to HP P2000
3 Ports from 7800 to 3 Servers
This way I will have room to scale out
Or can I free up few ports and connect 7800 with ISL's as another switch in the same fabric ?
I think that convert the blade switches to AG is a bad Idea. This is because the way that the FOS manages the traffic on AG links compared with normal ISL's.
So you have 4 7800. Thats nice! But as far as I know, the 7800 has up to 16 8Gb/s FC ports and six aditional 1GBe ports, that 6 ports are intended to ethernet connection.
But you still have some good choices.
If I understood your actual topology, you have two separate Bladecenter chassis, each one with only one 24 port switch (you dont have redundant access to the storages)
you could use two of your 7800s to create a small "core" an connect your bladecenters to it, and your storages to it.
The other two, you may save for a future expansion or to create a redundant core when you buy another bladeswitches for your chassis...