Re: Journaling pointless with today's hard disks?

Ian Stirling
2001-11-25T00:25:06Z

<snip>
> It could be that other drives have the capability to detect and write
> over sectors made bad by power off. Or maybe they lock out the sector
> and map to a spare. They might even have enough spin left to finish
> the sector correctly in more cases.
>
> So I doubt the issue is present in other drives, unless the issue is
> not really as big of one as we might think and the problems with IBM
> drives are something else.
>
> I do worry that the lighter the platters are, the faster they try to
> make the drives spin with smaller motors, and the quicker they slow
> down when power is lost.

Utterly unimportant.
Let's say for the sake of argument that the drives spins down to a stop
in 1 second.
Now, the datarate for this 40G IDE drive I've got in my box is about
25 megabytes per second, or about 50K sectors per second.
Slowing down isn't a problem.

Somewhere I've got a databook, ca 85 I think, for a motor driver chip,
to drive spindle motors on hard disks, with integrated
diodes that rectify the power coming from the disk when the power fails,
to give a little grace.

If written by people with a clue, the drive does not need to do much
seeking to write the data from a write-cache to dics, just one seek
to a journal track, and a write.
This needs maybe 3 revs to complete, at most.