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 R.
Important
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.
- Transport:
/sys/class/fc_transport/targetH:B:T/ port_id— 24-bit port ID/addressnode_name— 64-bit node nameport_name— 64-bit port name
- Remote Port:
/sys/class/fc_remote_ports/rport-H:B-R/ port_idnode_nameport_namedev_loss_tmo: controls when the scsi device gets removed from the system. Afterdev_loss_tmotriggers, the scsi device is removed.Inmultipath.conf, you can setdev_loss_tmotoinfinity, which sets its value to 2,147,483,647 seconds, or 68 years, and is the maximumdev_loss_tmovalue.In Red Hat Enterprise Linux 6,fast_io_fail_tmois not set by default, hencedev_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 untildev_loss_tmoexpires and the queue is unblocked.Iffast_io_fail_tmois set to any value exceptoff,dev_loss_tmois uncapped. Iffast_io_fail_tmois set tooff, no I/O fails until the device is removed from the system. Iffast_io_fail_tmois set to a number, I/O fails immediately whenfast_io_fail_tmotriggers.
- Host:
/sys/class/fc_host/hostH/ port_idissue_lip: instructs the driver to rediscover remote ports.
