>>>- The todo and intd directories get very big under high load. On one
>>>machine, I've seen it reach 1.5 megs (just the directory file, not the
>>>content of the directory). How does this impact performance?
>>
>>A lot. And deterimentally so. I'm guessing that your inject rate is
>>exceeding the ability of qmail-send to process the todo queue.
>
>That's true. But so what? Shouldn't qmail just queue these messages?
Correct. But mails are "staged" in 'todo' by qmail-queue. qmail-send moves
these mails into the queue-proper when it gets a chance. If todo grows
large, it's a sure sign that qmail-send isn't getting enough resources to
move these mails.
>What is the function of these directory anyway (todo, intd, mess, ...). I
>couldn't find any info on this. Why don't todo and intd have the same
>multidirectory structure as remote,...?
The INTERNALS doc explains how mails are moved into the queue, along with
plenty of discussion in the mail archives I suspect.
>>Having said that, at 20K per hour I'd be having a close look at your system
>>performance figures to see how your resources are going. How do you
>>interpret the results from iostat and vmstat?
>
>The disks seem OK.
How many tps? How close is that to the max for the disk(s) in question?
>Memory is certainely an issue. Each qmail-remote eats 1.5 megs (virtual
>mem, 1 megs resident) and there is only 128 megs on the machines.
How much paging? If any, is it to the same disk as the queue?
Certainly you want to make sure you have sufficient memory. What did vmstat
tell you about your paging?
Regards.
