On Tue, 07 Jun 2011 18:26:36 +0100, Orchid XP v8 wrote:

>>> So, essentially, your entire argument is "the user can eject the disk
>>> at any time, therefore it's unsafe to cache anything".
>>>
>>> Correct me if I'm wrong, but wouldn't the contents of the disk be
>>> irrepairably corrupted *anyway*? That's why there's a disk activity
>>> light; so you don't hit eject while it's still writing stuff.
>>
>> Having actually done this at several points in the past, I can assure
>> you that Darren is correct.  Caching removable devices tends to be
>> *very* bad for data integrity.
>>
>> That's why, for example, in Windows (and on Linux), you need to "safely
>> remove" USB flash drives - they are cached for performance reasons.
> 
> In which way is suddenly removing a USB flash drive different from
> suddenly ejecting a floppy disk?

Because people are used to ejecting a diskette when they've finished 
writing to it.  Sometimes you have to keep an old method around because 
of the habits people form.

> So why is it perfectly OK to cache a USB flash drive, but completely
> unthinkable to cache a floppy disk?

See above.

> (Also, I'm sure I saw somewhere a setting in Windows to select whether
> the "safely remove hardware" thing is optional or not. The default
> setting is worse performance in exchange for pulling the drive /not/
> completely screwing the filesystem. I'm guessing M$ found that too many
> people actually did this...)

Performance vs. reliability.  Traditional tradeoff.

Jim

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