> Then I want to take the remaining four drives from each server and make ONE logical drive out of all eight of them so that BOTH servers could share it as one drive.
Which OS would you use?
Should the data be mirrored between servers or otherwise made redundant, so that if one server is down the other could keep working? Or are you willing to accept the logical drive being inoperable unless both servers are alive and well???
What is the actual problem this set-up is supposed to solve?
On Linux, you won't even necessarily need FibreChannel HBAs: you can achieve the same thing with regular network cards and DRBD.
Note that DRBD only provides the disk device layer. To successfully use the disks as a filesystem on multiple hosts simultaneously, you will need to choose a filesystem type that allows such use.
The usual filesystems have a designed-in assumption that there are no other hosts accessing the filesystem at the same time. This allows efficient caching. If this assumption is violated, the per-host disk caches will eventually cause the applications to receive stale data, even if only one host has read/write access at a time.
(The read-only host caches the data it has read previously, and won't be informed that the changes made by the read/write host has invalidated the data in the cache of the read-only host. When this happens to filesystem metadata, the read-only host is likely to read the wrong blocks for at least some subsequent requests, resulting in applications receiving nonsensical or subtly corrupted data.)
For multi-host access, you will need a cluster filesystem, which coordinates the write operations across all the participating hosts.