Problems unmounting/fssyncking extern UFS filesystem
cswiger at mac.com
Tue Nov 28 11:38:06 PST 2006
On Nov 27, 2006, at 8:41 AM, Kevin Oberman wrote:
>> As far as I know, that's not different from calling "sync"
>> just once. It might make more sense to put a little sleep
>> between the sync calls, though.
> The traditional mantra was
> and not sync;sync;sync. The reason was timing. By entering the sync
> command three times as fast as anyone could type, the sync could
> reliably complete.
Agreed. Although I've heard rumors that some systems treated 3 syncs
as some sort of special case, but I've never seen anything in code to
support the notion.
> That mantra is about 25 years old, so its validity on modern
> hardware is
> questionable, but the need for a delay is very real. I would suggest
> something like: sync && sleep 5
The other choice would be to make sync [or the sync(2) system call,
more precisely] blocking, so that it does not return until the buffer
cache has been flushed and all dirty pages in VM have been written to
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