2.9. Devices

The Red Hat Enterprise Linux 6.2 Emulex FC (lpfc) driver does not support firmware downloads for LPe1600x 16 Gbit/s Fibre Channel adapters. Please consult your OEM for instructions on how to download new firmware on these Fibre Channel adapters.

iSCSI and FCoE boot support on Broadcom devices is not included in Red Hat Enterprise Linux 6.2. These two new features, which have been added to the bnx2i and bnx2fc Broadcom drivers in Red Hat Enterprise Linux 6.2, remain a Technology Preview until further notice.

Starting with Red Hat Enterprise Linux 6.0 and later, kexec kdump supports dumping core to the Brtfs file system. However, note that because the findfs utility in busybox does not support Btrfs yet, UUID/LABEL resolving is not functional. Avoid using the UUID/LABEL syntax when dumping core to Btrfs file systems.

The persistent naming of devices that are dynamically discovered in a system is a large problem that exists both in and outside of kdump. Normally, devices are detected in the same order, which leads to consistent naming. In cases where devices are not detected in the same order, device abstraction layers (for example, LVM) essentially resolve the issue, through the use of metadata stored on the devices to create consistency. In the rare cases where no such abstraction layer is in use, and renaming devices causes issues with kdump, it is recommended that devices be referred to by disk label or UUID in kdump.conf.

The trace-cmd service does start on 64-bit PowerPC and IBM System z systems because the sys_enter and sys_exit events do not get enabled on the aforementioned systems.

trace-cmd's subcommand, report, does not work on IBM System z systems. This is due to the fact that the CONFIG_FTRACE_SYSCALLS parameter is not set on IBM System z systems.

Red Hat Enterprise Linux 6.1 and later enter processor power-saving states more aggressively. This may result in a small performance penalty on certain workloads. This functionality may be disabled at boot time by passing the intel_idle.max_cstate=0 parameter, or at run time by using the cpu_dma_latency pm_qos interface.

Red Hat Enterprise Linux 6 only has support for the first revision of the UPEK Touchstrip fingerprint reader (USB ID 147e:2016). Attempting to use a second revision device may cause the fingerprint reader daemon to crash. The following command returns the version of the device being used in an individual machine:

~]$ lsusb -v -d 147e:2016 | grep bcdDevice

The Emulex Fibre Channel/Fibre Channel-over-Ethernet (FCoE) driver in Red Hat Enterprise Linux 6 does not support DH-CHAP authentication. DH-CHAP authentication provides secure access between hosts and mass storage in Fibre-Channel and FCoE SANs in compliance with the FC-SP specification. Note, however that the Emulex driver (lpfc) does support DH-CHAP authentication on Red Hat Enterprise Linux 5, from version 5.4. Future Red Hat Enterprise Linux 6 releases may include DH-CHAP authentication.

The recommended minimum HBA firmware revision for use with the mpt2sas driver is "Phase 5 firmware" (that is, with version number in the form 05.xx.xx.xx). Note that following this recommendation is especially important on complex SAS configurations involving multiple SAS expanders.