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My server log displays the following error messages in RED:

kernel:  sda: sda1 sda2
kernel: sd 0:1:0:0: [sda] No Caching mode page found
kernel: sd 0:1:0:0: [sda] Assuming drive cache: write through
kernel: sd 0:1:0:0: [sda] Attached SCSI disk

I am using Seagate hard disk ST3300657SS with RAID 1 configuration. I have read the answer in this question which mentions:

In your case the device doesn't have a caching mode page, so the kernel assumes there is no caching of reads or buffering of writes, and that therefore writes to the device will be "write through," i.e. will go directly to the media.

Is this error a hardware issue that needs rectification?

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1 Answers1

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No, this is not a serious error, it is not actually an error at all. All that this indicates is that your drive's SCSI mode pages don't contain an entry for caching. A mode page allows reading metadata related to the device, and changing the settings of the device, for example, to disable or enable write caching.

In this case, your device does not provide information about any underlying write caching mechanism. This could be for a variety of reasons, most likely that either the device may be passed through an interface which presents itself as a SCSI device, but does not expose any cache (for example, if you were exposing the drive using a USB enclosure), or the device may simply have no cache (although this seems to not be true for your particular device).

Chris Down
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  • Hi Chris, is this because my hard drives are connected to the RAID controller and therefore not exposed? – Question Overflow Jun 21 '14 at 06:07
  • @QuestionOverflow If you're using hardware RAID, that's quite possible. – Chris Down Jun 21 '14 at 07:20
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    This also happens when a USB pen drive is used. Why this silly message would appear at all with flash drives escapes me, though. A simple fork that suppresses this message when the device is a USB memory stick would do the trick, but of course, this would be too easy. – syntaxerror Oct 07 '14 at 13:49