topic Re: What SAN ?? in Disk Enclosures

What SAN ??

Darren Chambers_1 — Tue, 17 Sep 2002 12:46:12 GMT

Hello Folks,
We have two storage arrays, an Hitachi & an XP256. At the moment approximately 20 hosts look at one OR the other array. We have four silkworm Brocades, a pair for each array, our hosts are VPAR machines, they have two fibre cards each, one plugged into each brocade pair (Hope this makes some sense !?). I now need all of the hosts to see both arrays ! If I plug one fibre card into one brocade of each brocade pair I'll have poor fail over capability. I could add more cards but this is not ideal. Does anyone have a decent idea for a solution or maybe a pointer to some useful documentation ??? Thank You, Darren Chambers

Re: What SAN ??

Leif Halvarsson_2 — Tue, 17 Sep 2002 13:25:29 GMT

Hi
I have seen configuration examples with cross-connected switches (I think this is what is called FC-fabric).

If the switch pairs is called a1,a2 and b1,b2

connect a1 to b1 and b2
connect a2 to b1 and b2

Then all servers should be able to see all disks.

In this link is an example of a more complex fabric.

http://www.networkcomputing.com/1109/1109ws1.html

Re: What SAN ??

Ashwani Kashyap — Tue, 17 Sep 2002 14:08:45 GMT

I think its calles ISL ( Inter switch link ), where you connect the switches among themselves.There are several architecture to this. You can have cascaded switches , meshed switches , or layered switches i.e switches in each layer performing different functions .

Before you do this , beware of the domain ID'd of the switches . THey have to be unique on each switch before ISL'ed . Also there is a chance that your device files may change .

Re: What SAN ??

Seth Parker — Tue, 17 Sep 2002 21:47:32 GMT

Check out this link:
http://www.hp.com/products1/storage/products/san/fibreswitches/SAN_Design_RefGuide-AA-RMPNE-TE.pdf

It's a rather large document that has some nice diagrams on SAN topologies. The mesh diagram they show would mean adding 2 more connections to each switch so that it can connect to both of the switches in the other pair.

Hope this helps and good luck!