Re: [ANNOUNCE] Ramback: faster than a speeding bullet

[Ric Wheeler]

Pavel Machek wrote:
> Hi!
>
> > > Everyone who has write cache turned on for their hard drives is
> > > running in a mode similar to ramback anyway (except for when the file
> > > system is set to force writes to the platter, but that is rare).
> > > Admittedly, software crashes rarely cause the write cache to be lost,
> > > but hardware failures do, practically every time.
> > On the contrary - the hard disk cache is managed by the barrier logic in
> > the kernel, and the ordering even on failures is fairly predictable.
>
> Well, not even all modern hdds support barriers... It would be really
> nice to have _safe_ settings by default here...

The only really safe default is to disable the write cache by default or 
possibly dynamically disable the write cache when barriers are not 
supported by a drive. Both have a severe performance impact and I am not 
sure that for most casual users it is a good trade.

ric
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