78 TroubleshootingRed Hat Enterprise Linux Operating System ErrorsTable 6-6 describes an issue related to the Red Hat® Enterprise Linux operating system.Table 6-6. Linux Operating System ErrorError Message Suggested Solution kernel:sdb: asking for cachedata failed kernel:sdb: assuming drivecache: write throughThis error message displays when the Linux Small Computer System Interface(SCSI) mid layer asks for physical disk cache settings. Because the PERC 5controller firmware manages the virtual disk cache settings on a per controller anda per virtual disk basis, the firmware does not respond to this command. Thus, theLinux SCSI mid layer assumes that the virtual disk's cache policy is write-through.SDB is the device node for a virtual disk. This value changes for each virtual disk.See the section "Setting Up Virtual Disks" on page 58 for more information aboutwrite-through cache.Except for this message, there is no side effect to this behavior. The cache policy ofthe virtual disk and the I/O throughput are not affected by this message. The cachepolicy settings for the PERC5 SAS RAID system remain the settings you havealready chosen.Driver does notauto-build into newkernel after customerupdates.This error is a generic problem for DKMS and applies to all DKMS-enabled driverpackages. This issue occurs when you perform the following steps:1 Install a DKMS-enabled driver package.2 Run up2date or a similar tool to upgrade the kernel into the latest version.3 Reboot into the new kernel.The driver running in the new kernel is the native driver in the new kernel. Thedriver package you once installed in the new kernel does not take effect in the newkernel.Perform the following procedure to make the driver auto-build into the new kernel:1 Type:dkms build -m -v version> -k2 Type:dkms install -m -v -k3 Type the following to check whether the driver is successfully installed in the newkernel:DKMSThe following details appear:, , kernel version>:installedDell_PERC5_UG.book Page 78 Tuesday, February 13, 2007 6:02 PM
