some questions about Tunning FreeBSD

[Chuck Swiger]

Vahric MUHTARYAN wrote:
> 1)in tuning man siad that " Setting vfs.vmiodirenable improve the performans
> of sevices that manipulating a large number of file like Web Cache,large
> Mail System and News System " But I don't agree with it for mail system, or
> What type of mail systems can imporved with this settings ...
[ ... ]

Consider using Maildir-style mailboxes rather than MBOX-style. [cf procmail]

> 2)Can I set Kern.maxfilesperproc=0 because I don't want to seperate
> maxfilesize for seperate process ?! I mean I don't want to limit it for any
> process ?! 

I'm not sure whether 0 means "unlimited" for that parameter.  It's safer to 
set a reasonable limit to prevent a malicious or runaway process from hogging 
finite resources; set it to a few thousand or so and not worry about it. 
Unless you've got a monster news server or squid or something which wants lots 
of descriptors...

> 3)I think setting kern.pc.somaxconn is not necessary because all programs
> can handle their self listen queue size like Apache and Mail Programs . 

Yes, but it reasonable for the system (aka root) to set a maximum that no user 
process can exceed, just as other resource limits are handled-- man getrusage.

> One sentence disturb me in tunning man, "Larger listen queue also do a
> better job of fending off denial service attack" I can't imagine How ?!

While your inbound pipe might be full of DoS traffic, there may still be some 
valid requests coming in, as well as local network traffic which is still 
getting through.  A longer listen queue lets the machine at least try to 
service those connections rather than having them get dropped....

-- 
-Chuck