On Monday 11 October 2004 02:13 am, Ivan Popov wrote:
> Hello Jerry,
>
> > Site 1                                      Site 2
> > ------                                      ------
> > MTA gateway                                 MTA gateway
> > (and coda client)                           (and coda client)
> >
> >
> > MTA server                                  MTA server
> > (coda client     / coda volume(s) for \     (coda client
> >    and           |                    |      and
> > coda server)     \ maildir storage    /     coda server)

I'm back. Coda seems to be the best technology to implement this, so I 
am going to have it part of my Test Plan A.

> > Q1: Can T1 speed adequately support two Coda servers?
>
> Is it adequate for at least twice your mail traffic?

Should be, and if not we can expand...

> > Current size of the maildir's is 21 GB, but growth is expected.
>
> Be aware that you cannot have a single directory bigger than several
> thousand entries (directory size is limited to 256K I think).
> It is probably the biggest concern for maildir-based installations.

Per ftp://www.coda.cs.cmu.edu/pub/coda/Announcement.6.0.6
"- Allow volumes to contain up to 512K files (previous limit was 256K)."

So it looks like I install 6.0.6 to start the testing...

However, I would still like an actual value for the maximum number of 
files in a single directory.

Another list member's suggestion was to modify the MTA to hash into 
multiple sub-dirs. That won't happen, as it would also require changes 
to POP3/IMAP servers, and I want to stick with the released code of my 
mail software.

> Be also aware about server file number limit. 21G data should be ok,
> twice as much (in small files) will be probably too much if you do
> not distribute data between several servers.

I assume this refers to the "volume" limit quoted above... In fact we do 
have 575000 files stored now, so I'll be splitting storage between 
multiple volumes in any case.

> > Q2: What are practical size limitations of Coda volumes?
>
> According to Jan there shouldn't be any, though you probably do not
> want to have huge volumes. I think at least some operations on a
> volume are serialized, so the bigger volumes, the bigger risk for
> delays when client processes wait for each other.

The only clients will be the other mail gateways, so I don't see this as 
a big issue. (though, now that I think about it, direct access to 
maildir's from my Fedora desktop could be fun... :-)

jerry