Re: Hashed mailboxes ?

[Matti Aarnio <mea@nic.funet.fi>]

> Hi,
> 
> does anybody know about some local delivery agent to make mailboxes
> 'hashed' too, i.e. instead of /var/spool/mail/asid use something like
> /var/spool/mail/a/s/asid ? The latest 'qpopper' supports such mailboxes
> structure, and it is vital for big sites with more than 10,000 clients. I
> have found that Zmailer till now supports hashing for queue spool only. I
> can probably hack 'mailbox' transport, but maybe this feature is already
> done by somebody ? 

	The best way (IMO) is to use  cyrus-imap server, however
	alternate schemes a'la qpopper's two-level-hash are possible.
	Perhaps something like it can be added into the mailbox program.

	I do think there is no single everywhere applicable method,
	thus I have not implemented anything.  (Well, a strong hash
	plus some 1-2 level a-z subdirectory names -hash might do
	it...)

	However I did study the uniformity of the distribution of
	the accounts per first-letter/first+second-letter hashes,
	and didn't like them at utu.fi:  (Uniform average: 438.4)

		 981 a
		  32 b
		  68 c
		  54 d
		 450 e
		  20 f
		  27 g
		 686 h
		 167 i
		1358 j
		 936 k
		 367 l
		1712 m
		 212 n
		 160 o
		 876 p
		   6 q
		 430 r
		1038 s
		1421 t
		  80 u
		 266 v
		  13 w
		   5 x
		  15 y
		  10 z

	Sadder effect is on using 1st and second chars; median is 3
	mailboxes, and the big-hash end is:  (Uniform average: 16.8)
	(sorted in reverse appearance frequency order, and counted)
		...........
		300   74 li
		301   76 kr
		302   99 ve
		303  102 ra
		304  112 su
		305  117 le
		306  118 me
		307  119 el
		308  122 vi
		309  132 la
		310  134 ar
		311  139 si
		312  170 ni
		313  173 tu
		314  187 to
		315  202 pi
		316  215 ki
		317  236 ri
		318  243 ta
		319  259 te
		320  293 pe
		321  309 jo
		322  312 he
		323  314 ha
		324  336 pa
		325  415 ju
		326  457 ja
		327  488 ti
		328  548 ka
		329  611 an
		330  622 sa
		331  639 mi
		332  868 ma

> With best regards,
> 
> -------------------------------------------------------------
> Alexandre Sidorenko		Senior System Administrator
> asid@microtec.net

	/Matti Aarnio <mea@nic.funet.fi>