On Fri, Jan 22, 1999 at 09:47:48AM -0500, Jason Middlebrooks wrote:

...

Is Microsoft exchange supported on the netapp filers?

Actually, I think exchange requires that all data be stored on local drives, just like SQL server does.

--

While we're on the subject of mail, I was thinking of moving our sendmail spool area from a drive local to the Sun mail server to one of our NetApp boxes. Anyone have any pros/cons regarding NFS mounting the mail spool to the mail server?

aTdHvAaNnKcSe

On Fri, 22 Jan 1999, Mike Horwath wrote:

I did that here with approximately 12000 mailboxes.

Now that server (F720) is sustaining 2000+ ops a sec and is not nearly as responsive as it used to be.

Monolithic mailbox files or MH/MailDir-style mailboxes (one message per file)? Is your /var/spool/mqueue on local disk or NFS? How much of that NFS traffic is from POP3 and how much is from SMTP? I'll bet most of it is POP3. Sendmail only has to append messages to mailboxes. Most POP3 servers have to scan the entire mailbox every time someone connections, to get headers and a message count. Some POP3 servers will make a copy of the entire mailbox, zero out the original (in case more mail comes in), then copy undeleted messages back to the original when the user quits. That's potentially four times the size of your mailbox going across NFS, just to see if new mail has arrived. How many of your users have their mail programs set to check for new mail every 5 minutes? ;-)

This is my observation from watching our virtual POP3 hosting servers (which uses the traditional Berkeley-style monolithic mailboxes) and our dialup POP3 servers (which use MailDir-style mailboxes, with a dbm index file... no more header scanning!). Our four Netapps F230's on the dialup side each see 250 to 320 NFS ops/sec during peak times, with a much larger customer base.

The POP3 server reads in a small db index file that contains the message count, UIDL ids and line counts, reads individual mail messages only when required by the user, and issues an unlink() to delete a message. I figure this reduces disk traffic by about 95% compared to the standard popper or qpopper daemon, assuming your users tend to leave a meg or so of mail on the server.

I've run continuous POP3 benchmarks on the server: 99% of the time, it takes just under 4.00 seconds to open a connection to the POP3 port, issue USER, PASS, LIST, UIDL, RETR a 1.3K test message and finally QUIT. That's about three dozen NFS operations going over the wire, for a mailbox with 48 messages totalling 1100K. If the POP3 server has to read, write, re-read and re-write the mailbox, you would be seeing several hundred NFS ops plus all the associated bandwidth.

Now for my question: is there a freely available POP3 server that employs an index db file and MailDir-style mailboxes? The one mail system I am using contains proprietary hacks to sendmail and popper.

While we're on the subject of mail, I was thinking of moving our sendmail spool area from a drive local to the Sun mail server to one of our NetApp boxes. Anyone have any pros/cons regarding NFS mounting the mail spool to the mail server?

Yes: use maildir format for mail delivery over NFS. NFS locking isn't good enough to handle mbox-style (i.e. sendmail, procmail, etc) mail delivery over networked drives.

Nick Hilliard Ireland On-Line System Operations

+--- In a previous state of mind, Jim Davis jdavis@CS.Arizona.EDU wrote: | | On Fri, 22 Jan 1999, Gordon Keegan wrote: | | > one of our NetApp boxes. Anyone have any pros/cons regarding NFS | > mounting the mail spool to the mail server? | | Locking has to be absolutely, positively bombproof or you can lose mail. | Not just individual messages but whole mailboxes. Users tend to get | disgruntled when that happens.

Don't rely on the locking to work correctly for critical apps like mail. You will get bitten in the most horrible of ways when you least expect it.

| mail.local as your local delivery agent; procmail is allegedly more robust | (if you use dot locking) but I'd still be a bit leery.

It is still not an atomic operation, so you are still exposed.

The trick is to get away from the mailbox format. Use the maildir format (ala qmail). Each mesg has a unique ID (no locking needed for delivery) and it makes enforcing mail quotas (age of mesg) much simpler.

If you use procmail as your delivery agent and you are not keen on dropping sendmail in favor of qmail, there are some patches and recipies for procmail that do the maildir delivery. You will need a new pop and imap daemon (look to qmail for these) that understands the maildir format.

The other beauty of using the maildir format (esp if your users mail around large items like word or excel docs) is that the POP daemon does not have to lock and copy the monolithic mbox for each user when he/she pop's their email. This will reduce the IO on your mail server quite a bit.

Alexei

Hi Mike and Jason,

...

Actually, I think exchange requires that all data be stored on local drives, just like SQL server does.

Please refer to:

Network Appliance And Sybase Deliver Data Management Storage Solutions For Database Environments

http://www02.netapp.com/news/level3b/news_rel_981012.html

-or-

Sybase, Network Appliance Deliver Adaptive Server-Based Data Management Storage Solutions

http://www-es1.sybase.com:80/inthenews/External_Item/1,1068,506,00.html

Bob

PS. Talk to your Sales Rep about Exchange!

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