Chapter 11. Using Fibre Channel devices
Red Hat Enterprise Linux 8 provides the following native Fibre Channel drivers:
11.1. Resizing Fibre Channel Logical Units
As a system administrator, you can resize Fibre Channel logical units.
Determine which devices are paths for a
Re-scan Fibre Channel logical units on a system that uses multipathing:
$ echo 1 > /sys/block/sdX/device/rescan
11.3. Fibre Channel configuration files
The following is the list of configuration files in the
/sys/class/ directory that provide the user-space API to Fibre Channel.
The items use the following variables:
- Host number
- Bus number
- Logical unit (LUNs)
- Remote port number
Consult your hardware vendor before changing any of the values described in this section, if your system is using multipath software.
Transport configuration in
- 24-bit port ID/address
- 64-bit node name
- 64-bit port name
Remote port configuration in
Controls when the scsi device gets removed from the system. After
dev_loss_tmotriggers, the scsi device is removed. In the
multipath.conffile , you can set
In Red Hat Enterprise Linux 8, if you do not set the
dev_loss_tmois capped to
600seconds. By default,
fast_io_fail_tmois set to
5seconds in Red Hat Enterprise Linux 8 if the
multipathdservice is running; otherwise, it is set to
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.
fast_io_fail_tmois set to any value except off,
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 the
Host configuration in
Instructs the driver to rediscover remote ports.
11.4. DM Multipath overrides of the device timeout
sysfs option controls the timeout for a particular iSCSI device. The following options globally override the
replacement_timeoutconfiguration option globally overrides the
recovery_tmovalue for all iSCSI devices.
For all iSCSI devices that are managed by DM Multipath, the
fast_io_fail_tmooption in DM Multipath globally overrides the
fast_io_fail_tmooption in DM Multipath also overrides the
fast_io_fail_tmooption in Fibre Channel devices.
The DM Multipath
fast_io_fail_tmo option takes precedence over
replacement_timeout. Red Hat does not recommend using
replacement_timeout to override
recovery_tmo in devices managed by DM Multipath because DM Multipath always resets
recovery_tmo, when the
multipathd service reloads.