Subject Re: [firebird-support] Data Lost...
Author Lester Caine
Geoff Worboys wrote:
> Hi Branden,
>> [...] When he turned the tablet PC back on,
>> all of the data he had entered that day was gone. [...]
> It seems very unlikely to me that the problem you describe
> would be the HDD hardware cache. While it can be a factor for
> data loss in power-failure or power-fault situations, I cannot
> imagine it would hold-up writing data for an entire day...
> unless there is some sort of fault in the drive firmware.
> To be honest I cannot really see Windows file system caching
> doing that either. The Windows system restore feature could
> be a factor if your database is held somewhere that Windows
> thinks it needs to protect.

It HAS been demonstrated in the past that Widows did not ACTUALLY write anything
to the disk until the application accessing the disk closed, or dropped the
connection to it. As soon as the connection was shut, the reported file size
would increase. Even with 'forced writes' on, pulling the plug DID loose the
whole of a days work! I could recreate it reliably on the bench!

Now this was W2k many years ago, and I don't know if you could recreate the
problem with a later service pack version, but I would not put it past M$
engineers - who have never really understood hardware - to introduce a
regression, and Helen has pointed out one, but I've seen other driver related
problems where it is not the hardware cache that is the problem, but rather
interaction between windows, driver software and the hardware.

Lester Caine - G8HFL
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