Re: sync & asyck i/o

[Andre Hedrick]

On Tue, 6 Feb 2001, Stephen C. Tweedie wrote:

> The ll_rw_block interface is perfectly clear: it expects the data to
> be written to persistent storage once the buffer_head end_io is
> called.  If that's not the case, somebody needs to fix the lower
> layers.

Sure in 2.5 when I have a cleaner method of setting up hooks to allow
testing and changing of the mode but you can not assume that this stuff is
off by default and will stay that way.

At this time I am working to clean up an IBM mess of drives that do random
dumping of the drive cache to the platters when power is pulled.  This is
a nice dirty errata that I have heard about but have never seen, but can
believe that it is real.  The painful part is now that drives have these
huge buffers of upto 4MB, we have only a second or two to hit the platters
before the head float and spindle sync for writing depart from the
allowable range and it does not get to disk....OOPS!

I suspect that with all of the new NVRAM HOSTS coming to market soon we
will see more fs death in the future until things settle.

Cheers,

Andre Hedrick
Linux ATA Development
ASL Kernel Development
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