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8 Gbps, and even 16 Gbps connectivity in single-, dual-, or quad-ported options. Older, obsolete
HBAs supported up to only 2 Gbps. Some HBAs supported by ESXi are the QLogic QLE2462 and
Emulex LP10000. You can i nd the authoritative list of supported HBAs on the VMware HCL at
www.vmware.com/resources/compatibility/search.php. For end-to-end compatibility (in
other words, from host to HBA to switch to array), every storage vendor maintains a similar
compatibility matrix.
Figure 6.7
A Fibre Channel
SAN presents LUNs
from a target array
(in this case an
EMC VNX) to a
series of initiators
(in this case a Cisco
Virtual Interface
Controller).
Although in the early days of Fibre Channel there were many types of cables and interopera-
bility of various Fibre Channel initiators, i rmware revisions, switches, and targets (arrays) were
not guaranteed, today interoperability is broad. Still, it is always a best practice to maintain your
environment with the vendor interoperability matrix. From a connectivity standpoint, almost
all cases use a common OM2 (orange-colored cables) multimode duplex LC/LC cable. The newer
OM3 and OM4 (aqua-colored cables) are used for longer distances and are generally used for
10 Gbps Ethernet and 8/16 Gbps Fibre Channel (which otherwise have shorter distances using
OM2). They all plug into standard optical interfaces.
The Fibre Channel protocol can operate in three modes: point-to-point (FC-P2P), arbitrated
loop (FC-AL), and switched (FC-SW). Point-to-point and arbitrated loop are rarely used today.
FC-AL is commonly used by some array architectures to connect their backend spindle enclo-
sures (vendors give different hardware names to them, but they're the hardware elements that
contain and support the physical disks) to the storage processors, but even in these cases, most
modern array designs are moving to switched designs, which have higher bandwidth per disk
enclosure.
As Figure 6.8 shows, each ESXi host has a minimum of two HBA ports, and each is physically
connected to two Fibre Channel switches. Each switch has a minimum of two connections to
two redundant front-end array ports (across storage processors).
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