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Re: Lost file-system story

Andy Ruhl <> writes:

> If solving your problem depends on sync frequency, I don't see why
> this shouldn't be managed by some knob to twiddle. Given that the
> crash scenario doesn't get worse depending on where the knob is or if
> the crash happens while the knob is working. If it does, it's
> pointless.

My sense is that Donald isn't complaining about why is the sync
frequency 30s instead of 60s; it's more bafflement at waiting 10-15
minutes with an idle disk and having the data not synced at all.
There's a historical period of 30s, and that seems both not often enough
not to cause trouble and often enough to not boggle users.

It may also make sense to have a syncer behavior that is low rate, to
not overwhelm asked-for IO, and to use most of the disk bandwidth when
it is on, and to let it be otherwise, for laptops.  But a basic
correctness property is almost certainly that if the disk is spun up and
is not in heavy use and lots of time passes, dirty buffers (data and
metadata) are written to disk.

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