On 08/13/2011 01:10 PM, Robin Horforth wrote:
> The import takes Dovecot (MailDir or mdbox format), or Panda IMAP (mix)
> about six minutes to complete.
I'll take your word for it.
> DBMail 3 took 4h 23m. Casual inspection of the system showed modestly
> high CPU usage in mysqld and dbmail-imapd (as well as the import perl
> command on occasion), but the Load Average didn't get too close to 1.0,
> let alone 2.0, which concerns me that I might have hit some kind of
> "busy wait" pathology.
How many concurrent IMAP connections are you using? A load below 1
indeed sounds suspicious.
>
> Have I picked the "wrong day" to check out a git version? Have I
> flubbed the MySQL configuration? The documentation says 250 inbound
> emails/second is possible - is this with a vast cluster comprised of
> very fast CPU/RAM/SSD hard disks?
That number is about retrieval. And then only on POP3. And a very old
number (dbmail-1.0?).
I'd be curious about more up-to-date numbers.
Also, I'm not at all familiar with IO performance on VMWare, but on Xen
IO really lags behind bare-iron databases. And thats no joke. On Xen
hosts running mysql-5.5 I need to keep thread-concurrency at 1 (read:
one) to keep throughput at acceptable levels with IMAP concurrencies
around 50-100 connections, POP3 around 10-20, with an added 5 LMTP
connections for insertions.
That said: dbmail will never be able to achieve the kind of numbers you
mention for dovecot or panda. The single-instance storage used for both
mime-blobs and header values, and fully indexed headers prevent it.
DBMail insertion is not about creating simple files in directories.
--
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