Linux – Difference between “blockdev –flushbufs” and “sync” on Linux

You forget one crucial thing, namely that your program will have to interact with the operating system to do anything interesting.

The conventions are different between Linux and OS X so the same binary cannot run as-is without essentially having a chunk of operating system dependent code to be able to interact with it. Many of these things are provided through libraries, which you then need to link in, and that means your program needs to be linkable, and linking is also different between the two systems.

And so it goes on and on. What on the surface sounds like doing the same thing is very different in the actual details.

This is described in some detail in the md(4) man page, section RECOVERY.

[...] a read-error will instead cause md to attempt a recovery by overwriting the bad block. i.e. it will find the correct data from elsewhere, write it over the block that failed, and then try to read it back again. If either the write or the re-read fail, md will treat the error the same way that a write error is treated, and will fail the whole device.

As for timeouts, while there are reports of drives getting kicked out if they were in standby, it's never actually happened for me. I have 7 HDDs which usually spin down (as the main system runs off SSD and can get by without HDD access for long periods of time) and it works without a problem (except that md wakes one drive after the other instead of all-at-once).

I guess it depends on what the other layers report to md.