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I have a laptop from 2010. When it boots a recent Linux kernel, I see two error messages on the screen:

sd 0:0:0:0: [sda] Asking for cache data failed
sd 0:0:0:0: [sda] Assuming drive cache: write through

The same message is displayed when I boot my another, even older laptop. I boot in quiet mode, which means no boot-up messages should normally appear, but these do. The hard drives in either seemingly work fine.

How serious is this message? Is this a sign of imminent hard disk failure? How do I make it go away?

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  • I doubt its serious at all. I suspect Ive seen them iften but its just background noise. If you are worried about the drives check what S.M.A.R.T says.
    – davidgo
    Jan 7 at 10:51
  • If I can just ignore it, why display it during quiet boot? Jan 7 at 19:02

2 Answers 2

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Nearly all modern harddrives have an onboard RAM cache to speed up operation. Since a RAM cache could be lost on an unexpected power outage, the existence, size and mode of this cache should be queryable from the host computer.

Older drives do not implement (either not correctly or not at all) this query, so the host "fails, asking for cache data". The host then assumes, that the cache is in write-through mode and continues.

If the drive behaves well, this is no problem whatsoever - if it does not, then an unexpected power outage might lose the last few writes. Most likely you would have already learned about that, as it would lead to more unexpected messages and maybe an emergency mode from time to time.

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There is a bug in Kernel version 5.15. Ignore it. It will probably be fixed in future versions.

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