[Mailman-Users] Hardware Requirements

[alex wetmore]

On Thu, 11 Jul 2002, Scott Courtney wrote:
> On Thursday 11 July 2002 01:42 pm, J C Lawrence wrote:
> > You might to look over the RFCs for SMTP and pay particular attention to
> > the bits about guarantees and transaction handling.
> [...]
> >
> > It tends to define a whole lot of sync() and open()/close() calls (which
> > latter force a buffer and inode flush).
>
> You're right, of course. It's been several years since I've needed to get into
> SMTP RFCs in that level of detail.

Here is the important section:

   When the receiver-SMTP accepts a piece of mail (by sending a "250 OK"
   message in response to DATA), it is accepting responsibility for
   delivering or relaying the message.  It must take this responsibility
   seriously.  It MUST NOT lose the message for frivolous reasons, such
   as because the host later crashes or because of a predictable
   resource shortage.

By my reading of this paragraph it is not acceptable to have a queue
on a RAM disk unless the disk is battery backed and won't be affected
by a server reboot.

Various companies, such as cenatek.com, make hardware that meet these
requirements.  It isn't very affordable though, and most servers would
probably do just as well with a well thought out RAID array (that
means avoiding RAID 5, which has very poor performance for small disk
writes, and SMTP servers are all about doing tons of small disk
writes).

alex