Chapter 26. Fibre Channel
This section discusses the Fibre Channel API, native Red Hat Enterprise Linux 6 Fibre Channel drivers, and the Fibre Channel capabilities of these drivers.
26.1. Fibre Channel API
Following is a list of
/sys/class/directories that contain files used to provide the userspace API. In each item, host numbers are designated by
H, bus numbers are
B, targets are
T, logical unit numbers (LUNs) are
L, and remote port numbers are
If your system is using multipath software, Red Hat recommends that you consult your hardware vendor before changing any of the values described in this section.
port_id— 24-bit port ID/address
node_name— 64-bit node name
port_name— 64-bit port name
- Remote Port:
dev_loss_tmo: controls when the scsi device gets removed from the system. After
dev_loss_tmotriggers, the scsi device is removed.In
multipath.conf, you can set
infinity, which sets its value to 2,147,483,647 seconds, or 68 years, and is the maximum
dev_loss_tmovalue.In Red Hat Enterprise Linux 6,
fast_io_fail_tmois not set by default, hence
dev_loss_tmovalue is capped to 600 seconds.
fast_io_fail_tmo: specifies the number of seconds to wait before it marks a link as "bad". Once a link is marked bad, existing running I/O or any new I/O on its corresponding path fails.If I/O is in a blocked queue, it will not be failed until
dev_loss_tmoexpires and the queue is unblocked.If
fast_io_fail_tmois set to any value except
dev_loss_tmois uncapped. If
fast_io_fail_tmois set to
off, no I/O fails until the device is removed from the system. If
fast_io_fail_tmois set to a number, I/O fails immediately when
issue_lip: instructs the driver to rediscover remote ports.