On Mon, 23 Dec 2002 14:52:23 +0300, Nikita Danilov said: > > But as Hans argues, usually these sequentional-read operations are ones most > > noticed because they are usually performed by humans: > > ls, tar, copy of a directory and this kind of stuff. > > Humans are so slow compared to the slowest hard drive that ls is the > least important thing to optimize.
Never had a 26-hour daily backup of a large mail spool, have you? ;)
Remember that 'tar' and copy of a directory are things that are likely to
be done as part of a production workload - and if you aren't using tar,
you still need to have *something* that does a stat() on every single file,
even if it's an incremental.
There's also resource contention issues - many systems are up 24x7, and
things like backups and the like have to be done on live filesystems during
off-peak hours. This means that if "off-peak" is 9PM-6AM, you have *two*
constraints: (1) the job has to finish in under 9 hours, (2) It has to consume
few enough resources that nothing else bogs down....
--
Valdis Kletnieks
Computer Systems Senior Engineer
Virginia Tech
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