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Dell PowerEdge RAID Controller 10 User’s Guide PERC H345, H740P, H745, and H840 Series Controllers

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Virtual disk policy is assumed as write-through error message

Error:
<Date:Time> <HostName> kernel: sdb: asking for cache data failed<Date:Time> <HostName> kernel: sdb: assuming drive cache: write through
Corrective Action:
The error message is displayed when the Linux Small Computer System Interface (SCSI) mid-layer asks for physical disk cache settings. The controller firmware manages the virtual disk cache settings on a per controller and a per virtual disk basis, so the firmware does not respond to this command. The Linux 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.

For more information about Write-Through cache, see Virtual Disk Write Cache Policies.

Except for this message, there is no effect of this behavior on normal operation. The cache policy of the virtual disk and the I/O throughput are not affected by this message. The cache policy settings for the PERC SAS RAID system remain unchanged.

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