How the SAN drives are shared in AAP cluster setup in sql server2005?

Hi All,

We have SQL Server 2005 cluster setup as follows:
3 node active/active/passive cluster with 1 instance on node1 and 5 instances on node3.node is passive.

Active(node1) Passive(node2) Active(node3)

INS1 INS2
INS3
INS4
INS5
INS6

Node1 has drives Node3 has drives

C-> OS INS2-> G->primary
D->Primary H->log ]Group2
E->secondary T->tempdb
F->log ]group1
Q->quorum
S->tempdb INS3-> I->primary
Y->msdtc J->log ]group3
Z->backup U->tempdb

INS4-> K->primary
L->log ]group4
V->tempdb

INS5-> M->primary
N->log ]group5
w->tempdb
INS6-> O->primary
p->log ]group6
R->tempdb


Group1,2,3,4,5,6 are groups in cluster administrators.

Here are the Issues:

1.The drives of node1 are also showing up in node3?(happend after doing some upgrade in SAN)->major issue
Is this Normal behaviour??and the drives of nod1 in node3 are not accessible?

2.If want to install more instances like instance7 we have no drive letters to assign?

3.How can we install 26 failover instances if we have this drive letter conflict?

Iam Not using Mount Points..