[Mimedefang] Re: "Please try again later"

[John Rudd]

On Sep 10, 2005, at 5:47 PM, David F. Skoll wrote:

> John Rudd wrote:
>
>> Hm.  Well, maybe not.  After adjusting that to 20 and 15, that's not
>> really helping.
>
> We'd have to see some log messages to figure out why there's an 
> overload,
> if in fact load is the issue.

The errors all pretty much looked like this one:

Sep 10 09:13:49 cats-mx1.ucsc.edu mimedefang-multiplexor[18967]: [ID 
760071 mail.warning] No free slaves
Sep 10 09:13:49 cats-mx1.ucsc.edu mimedefang[18981]: [ID 847421 
mail.error] Error from multiplexor: error: No free slaves
Sep 10 09:13:49 cats-mx1.ucsc.edu sendmail[19122]: [ID 801593 
mail.info] j8AGCBci019122: Milter: data, reject=451 4.3.2 Please try 
again later

That was with 10 slaves.

After I increased the number of slaves:

Sep 10 10:04:56 cats-mx1.ucsc.edu mimedefang-multiplexor[25403]: [ID 
760071 mail.warning] No free slaves
Sep 10 10:04:56 cats-mx1.ucsc.edu mimedefang[25416]: [ID 847421 
mail.error] Error from multiplexor: error: No free slaves
Sep 10 10:04:56 cats-mx1.ucsc.edu sendmail[25615]: [ID 801593 
mail.info] j8AH3aYw025615: Milter: data, reject=451 4.3.2 Please try 
again later


So, looks like it's that I don't have enough load capacity to have 
enough slaves running to keep up with my message flow.  On this 
hardware.


>> I'm thinking it might be that we run our front line mail servers on
>> tiny/hold hardware (sunblade 150's and sunfire v100's, 2 of each, and 
>> so
>> far I had only installed this on one of the sunblades).
>
> Yep; that's pretty old hardware.  As much as I love Sun, the sad fact
> is that commodity Intel hardware running Linux or FreeBSD beats the
> pants off SPARC hardware, at a fraction of the price.

Yeah.  But then we get into conflicts here about platforms.

If we switch away from being an "almost all Sun/Sparc shop", our boss 
wants to go with Linux (and, even within Linux, he wants to go with a 
Sun solution -- I think mostly for support contract reasons, which has 
to apply to more than just our mail servers, it has to go all the way 
across our datacenter).  My peer and I (the mail admins) want to go 
with FreeBSD or OS X.

(and, it's not even that our boss is anti-OSX ... it's what he uses on 
his desktop ... but he also recognizes that most of the rest of our 
sysadmin group (incl. the non-mail admins) don't know OSX specifics ... 
most of them don't know *BSD, either ... so it's hard to come up with 
good arguments there)

So, we stay in a Solaris/Sparc holding pattern for now.  But the 
v210/v240 boxes are actually pretty nice.  But, yeah, $/Hz is still 
better on Intel.  Or even PPC.


I wouldn't mind Linux so much if it wasn't such a moving target ... 
while it's not as fragile as windows, it seems like you need to do as 
much, if not more, patching and rebuilding on it in order to keep up 
with what's current ... and you almost have to do that if you want to 
remain compatible with any new features you need to implement.  If it 
were as easy as OSX ("click this button to see what updates are out 
there, check which ones you want, click update, sometimes you have to 
reboot"), that wouldn't be such a problem.  Though, I hear that 
recently a util has come out for various linuxes that is almost that 
easy, for keeping things fresh and up-to-date.  "Yum" or something?  
(and, of course, FreeBSD isn't much better on this front ... thus OSX: 
it's unix, it's bsd, it's easy to admin, what more could I want?)

On the other front, while I hear its memory manager and network (NFS in 
particular) code are getting more solid, for server work, I'm still 
gun-shy about the Linuxes I have used in comparison to FreeBSD for 
server stability.

(the last time I mentioned linux, I was very tongue in cheek about it, 
but now you see what my real concerns are)


> What's your daily mail volume?

We get around 150k messages/day, not including messages we reject 
through SBL+XBL (about 126k) or connections blocked through our 
greet-pause.  And, that's during the school year (those numbers are 
specifically the month of May).  Saturday morning should have been 
light and easy for our mail load.