Re: Loud "pop" coming from hard drive on reboot

[Tejun Heo]

Alan Cox wrote:
> > Not that simple.  Most disks don't spin up on SYNCHRONIZE_CACHE if its 
> > cache is clean.  Sadly some disks actually spin up when it receives spin 
> > down command while spun down to immediately spin down again, so we would 
> > be fixing problem for some number of disks while breaking others.  :-(
>
> Snoop the last command sent to the drive, that tells you if you can skip
> the cache flush ?

Thought about that and querying power state before doing shutdown 
sequence but things get somewhat ugly because shutdown sequence is 
driven from sd->shutdown().  We'll have to snoop both sync and shutdown 
commands and check whether the system is shutting down.  Also, I felt 
very uneasy about faking successful completion to SYNCHRONIZE_CACHE.

I dunno.  It's already too late for 2.6.21.  I was hoping we could get 
distros to update shutdown utilities in not-too-distant future but I 
have no experience with that.  Is that just a wishful thinking?

--
tejun
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