[Dovecot] The docs a re a bit weird on "Directory hashing"

[Timo Sirainen]

BTW. If you're using v2.2.3+ %N hash works better than the old %H hash. I updated http://wiki2.dovecot.org/Variables for it also.

On 8.8.2013, at 1.42, Eliezer Croitoru <eliezer at ngtech.co.il> wrote:

> In squid we use a double layer of hashed directories on the FS to allow
> storage of millions of files.
> I was reading the "Directory hashing" section but never understood it..
> since it's written.. in a way I could not understand.
> I am using this line:
> mail_location = maildir:/home/vmail/%d/%n/Maildir/
> 
> and I want to migrate to a hash based directory scheme.
> While trying to understand how that hash will work I stumbled a old
> thread at:
> http://www.dovecot.org/list/dovecot/2010-June/049695.html
> there they used:
> mail_location=maildir:/buzones/us.es/%1Hu/%2.1u/%n
> 
> so I assume it should be used like that:
> mail_location=maildir:/home/vmail/%H/%2.256Hn/%d_%n/Maildir/
> or:
> mail_location=maildir:/home/vmail/%1Mu/%2.1Mu/%d_%n/Maildir/
> 
> It's a bit hard to think alone so I hope you can assist me.
> 
> let say I want to follow the model of squid cache_dir which has:
> cache_dir aufs /usr/local/squid/var/cache/squid 40000 16 256
> 
> And means a two layers cache of max 16 directories on the first layer
> and 256 directories on the second layer.
> The above allows millions of files storage and can benefit from all ext4
> lower kernel levels of compatibly rather then do stuff on the user-land..
> Since I am not 100% sure that the scheme I understood is indeed what I
> think I assume the above will need a small correction.
> 
> Eliezer
>