hunting the fatty

[mancyborg at gmail.com]

On Tue, 10 Nov 2015 08:50:50 +0100
Christian Kivalo <ml+dovecot at valo.at> wrote:

> Hi,
> 
> On 2015-11-10 01:44, mancyborg at gmail.com wrote:
> > Hello dear list,
> > I've recently discovered 'doveadm stats' and I'm trying to use
> > "doveadm stats dump user" and "doveadm stats dump session"
> > to understand the pop/imap users that put more stress on the hard 
> > disks.
> > 
> > My problem is that some users refuse to delete their emails from the 
> > server,
> > so they keep 20GB of maildir files on the server, the webmail
> > (roundcube) takes forever to open the inbox,
> > the imap searches takes forever
> > and meanwhile all the users wait.
> > (already tried roundcube + memcache(d) but didn't help)
> 
> What is forever in your context?
> I'm using roundcube and a folder with about 78k mails opens in < 1 sec 
> unsorted. A folder with about 37k messages from a mailinglist and thread 
> sort takes < 3 sec. My roundcube shows 200 messages per page by default.
> On a side note, are you using an imap proxy for roundcube? It doesn't 
> help you with your dovecot problem but it speeds up roundcube.
> 
> To speed up imap searches i can recommend to implement fts-solr with 
> dovecot (or maybe fts-elasticsearch, am wanting to try that but solr 
> works...). That will speed up your searches after mailboxes are indexed.
> 
> > So my problem is not the storage usage itself:
> > I don't care if the user gets tons of emails with big attachments;
> > my problem is when the user opens / searches an imap folder with more
> > than 10K mails
> > and iostat util goes 100% for minutes.
> 
> Dovecot should be very quick to open even folders with a huge amount of 
> files due to its indexes.
> 
> I'm unable to reproduce any significant numbers in iostat when accessing 
> large mailfolders with roundcube.
> 
> Whats your configuration, filesystem, ...
> 
> > So I've enabled dovecot's stats and enjoying "doveadm stats top",
> > "stats-top.pl" and "doveadm stats dump user/session",
> > but talking about "doveadm stats dump user" and its output fields:
> > 
> > user	reset_timestamp	last_update	num_logins	num_cmds	user_cpu	sys_cpu	min_faults	maj_faults	vol_cs	invol_cs	disk_input	disk_output	read_count	read_bytes	write_count	write_bytes	mail_lookup_path	mail_lookup_attr	mail_read_count	mail_read_bytes	mail_cache_hits
> > 
> > I'm not sure which of those fields can help me
> > and I can't find any relevant documentation.
> > 
> > So here are my questions:
> > 
> > 1. is there a documentation for those 21 fields and for 'doveadm
> > stats' in general ?
> > 2. what's the difference between disk_output, read_bytes, read_count
> > and mail_read_bytes ?
> > 3. which field of those is, in your opinion, more representative for
> > expressing the workload that gives me problems ?
> > 4. which settings do I need to store 1 week worth of stats ?
> > 
> > I'm currenty using the 'standard' values:
> > 
> >   stats_refresh = 30 secs
> >   stats_track_cmds = yes
> >   stats_memory_limit = 16 M
> >   stats_command_min_time = 1 mins
> >   stats_domain_min_time = 12 hours
> >   stats_ip_min_time = 12 hours
> >   stats_session_min_time = 15 mins
> >   stats_user_min_time = 1 hours
> > 
> > Can you please tell me the correct parameters to store 1 week of stats 
> > ?
> 
> For stats somebody else has to jump in, i have only enabled the plugin 
> to see what to get out of it but not made any use of it.
> 
> Please share your doveconf -n output
> 
> > Thank you,
> > Mike
> 
> regards
> christian

By 'forever' I mean more than 1 minute.

So there is no documentation / manual for 'doveadm stats' ?
Do I have to read the source to know which field does what ?

I mean the output fields of "doveadm stats dump user":

user	reset_timestamp	last_update	num_logins	num_cmds	user_cpu	sys_cpu	min_faults	maj_faults	vol_cs	invol_cs	disk_input	disk_output	read_count	read_bytes	write_count	write_bytes	mail_lookup_path	mail_lookup_attr	mail_read_count	mail_read_bytes	mail_cache_hits

what's the difference between disk_output, read_bytes, read_count and mail_read_bytes ?

(sorry to restate the same question, just making sure about it)

Thank you,
Mike