[clue-tech] NFS/server tuning with mail-ldap and maildirs

[Roy J. Tellason]

On Thursday 16 June 2005 03:42 pm, Adam bultman wrote:
> Greetings.
>
> A few questions for you cluesters out there:
>
> I'm working on getting qmail-ldap, courier-imap/pop3 on serverblades, with
> NFS mounted maildirs. However, when mailboxes get larger than a few
> thousand, things slow down a great deal, more than they should for a system
> like that.
>
> The server will either spend time with imapd at about 10% usage, with it
> waiting on the network, or imapd will take up ALL the cpu, and spin for
> quite some time.
>
> My configuration is this:
>
> Netapp, with gigabit connection to the switch.
>
> Server: 800 MHz serverblade, 512 MB RAM, 100Mbit connection to switch.

<...>

> Are there more effective NFS options for these servers to use?  Right
> now, I'm using soft, noatime, tcp as my options. I don't know if using
> TCP is any *faster*, or if setting the rsize or wsize will help any either.

<...>

> Any ideas would be most appreciated.  I'm wondering if there's a
> fundamnetal speed problem that I won't be able to overcome with more
> serverblades, or if there's other ways I could squeak more performance out
> of them.

I too am seeing a serious performance hit with having moved my mail setup from 
all-in-one-box to using nfs,  though I'm not using anywhere near the hardware 
capabilities you're talking about here,  just a small home LAN setup.  I've 
found that keeping stuff with fairly short expiration times (and therefore a 
smaller number of messages overall) seems to help,  but aside from that I'm 
not sure what to try next either.

I will be looking at other replies to your post with some interest.