Date: Tue, 16 Feb 1999 19:39:55 -0500 From: "Ben Goodwin" <ben@hamsterville.ultranet.com> To: <freebsd-isp@FreeBSD.ORG> Subject: Re: DPT 3334UW RAID-5 Slowness / Weird FS problems Message-ID: <009701be5a0e$0a8b5ce0$174f06d1@hamsterville.ultranet.com> References: <36C88CC6.E1621F6F@spacemonster.org> <19990216105959.P2207@lemis.com>
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> > The user directories for delivery are broken out into 1st letter, 1st
> > two letters, username (i.e.: /home/u/us/username) to speed up dir
> > lookups already.
>
> I'd guess that these would end up in cache anyway, so you shouldn't
> see much improvement with this technique.
On the contrary; file-lookups are a flat scan. Breaking the lookup into a
hierarchy achieves a hashing effect; with 40,000 users, my server went from
(under flat-directory architecure) LA's of 4-8 and toppling over very easily
on load spikes, to LA's of 0.5 to 1 and humming along w/out noticing
anything. For anyone doing serious sendmail/pop activity, I highly
recommend it.
-=| Ben
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