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/sys/class/fc_host entries missing on a few RHEL 4 and 5 systems


/sys/class/fc_host entries missing on a few RHEL 4 and 5 systems


I am seeing that the fc_host class entries are not present in case of a few RHEL 4 and 5 systems. Is this a configuration issue? Can you please provide me the details on how this issue can be resolved?


Is this an issue with the version of the operating system or the HBA drivers?

Honored Contributor

Re: /sys/class/fc_host entries missing on a few RHEL 4 and 5 systems

It depends on kernel and HBA driver versions. It reflects the continuous and distributed nature of Linux development.


On RHEL 4, the /sys/class/fc_host was newly invented and some driver versions did not use it at all or had only the bare minimum of entries in it. Emulex drivers offered some useful information in /sys/class/scsi_host instead of /sys/class/fc_host. Some Qlogic driver versions used neither /sys/class/fc_host nor /sys/class/scsi_host for FC information, preferring to use Linux 2.4.* kernel style /proc/scsi/qla2xxx/* instead.


Within the RHEL 5 release cycle, the situation is better: a standard layout for FC information is starting to take shape, but there are still some inconsistencies: for example, while Emulex drivers placed the card firmware version information to /sys/class/scsi_host/host*/fwrev, Qlogic used /sys/class/scsi_host/host*/fw_version instead.


I cannot check at the moment, but I think you'll see still more standardization in fc_host class entries in RHEL 6.