Fibre Channel - high-speed block storage

Fibre Channel is the original SAN protocol, providing block storage over dedicated optical networks. It is more expensive than iSCSI but offers lower latency and higher throughput. It is the right choice for high-performance databases and mission-critical workloads.

How Fibre Channel works

Fibre Channel is a dedicated network protocol with its own switching infrastructure (FC switches), HBAs (host bus adapters), and cables (typically optical fiber). The host sees FC LUNs as block devices, just like local disks or iSCSI LUNs.

$ lsblk -o name,size,type,tran

NAME    SIZE TYPE TRAN
sda    100G disk fc
sdb    100G disk fc
sdc    100G disk fc
sdd    100G disk fc

FC zoning

$ systool -c fc_host -v

Host bus adapter path: /sys/class/fc_host/host0
Class:    fc_host
Fabric name: 0x100000051ee3b540
Symbolic name: server01.example.com
Port state: Online
Speed: 16 Gbit

FC zoning is the security and isolation mechanism. A zone is a set of WWNs (World Wide Names) that can communicate. Production zoning isolates workloads and limits blast radius.

Multipath over FC

$ multipath -ll

mpath0 (3600508...) dm-2 NETAPP,LUN
size=500G features='1 queue_if_no_path' wp=rw
|-+- policy='round-robin 0' prio=1 status=active
| |- 1:0:0:0 sda 8:0   active ready running
| `- 1:0:1:0 sdb 8:16  active ready running
`-+- policy='round-robin 0' prio=1 status=enabled
|- 1:0:2:0 sdc 8:32  active ready running
`- 1:0:3:0 sdd 8:48  active ready running

Knowledge check