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

[Adam bultman]

Roy J. Tellason wrote:

>On Thursday 16 June 2005 03:42 pm, Adam bultman wrote:
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>>Greetings.
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>>A few questions for you cluesters out there:
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>>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.
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>>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.
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>>My configuration is this:
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>>Netapp, with gigabit connection to the switch.
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>>Server: 800 MHz serverblade, 512 MB RAM, 100Mbit connection to switch.
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>>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.
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>>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.
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>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.
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>I will be looking at other replies to your post with some interest.
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Well, I've been doing more research, and finding that people are usually
using slower machines for their smtp servers, and putting more muscle
behind their imap/pop servers. At any given time, the SMTP server might
be procssing a few dozen messages, maybe a hundred on a busy box, but
imap will pretty much be constant, and high-demand.

I'll be testing some of it in the upcoming weeks, and we'll see how
things work.  I'm expecting to find that the slower systems (800 Mhz
blades) are more than acceptable for SMTP work, but not quite cut out
for the imap/pop3 work.

I'm thinking that for more responsive imap/pop3, I'll need more RAM, a
faster CPU, and ideally, a gigabit connection to reduce latency on the
network (hopefully crossover)

I'll keep you all posted.

Adam