Thanks - I'll give these a try should it happen again.

Jeff

On 9/17/2017 3:10 PM, Eric Broch wrote:

And, here's another one:

mysql -u root -ppassword -BNe "select host,count(host) from processlist group by host;" information_schema

Explanation:

Display the number of connections to a MySQL Database

Count the number of active connections to a MySQL database.

The MySQL command "show processlist" gives a list of all the active clients.

However, by using the processlist table, in the information_schema database, we can sort and count the results within MySQL.



On 9/17/2017 11:33 AM, Jeff Koch wrote:
Eric - thanks !  Jeff

On 9/17/2017 11:14 AM, Eric Broch wrote:

Hi Jeff,

Here are some commands you can run to determine the number of connections (to determine if this is the issue) to the MariaDB in the event that this happens again:

1) echo "show full processlist" | mysql -u root -ppassword

2) doveadm who

3)  ps aux | grep vpopmail | grep dovecot

Eric


On 9/15/2017 4:02 PM, Jeff Koch wrote:
I raised it to 300 but we're a little concerned about all these root sessions. Could they be a form of break-in attempt and why would they affect mysql to the point that dovecot could not connect. And what the heck is a 'user-89.slice. vpopmail is usually user 89.

Jeff

On 9/15/2017 5:57 PM, Eric Broch wrote:

I think I'd try upping the connection count, what's it at 151?


On 9/15/2017 3:25 PM, Jeff Koch wrote:
Nope.

But I did see this strange series of entries in /var/log/messages - which started at 12:03 and continued to 12:15. This was the same period that dovecot was complaining that it couldn't connect to mysql

Sep 15 12:04:01 vid systemd: Started Session 208671 of user root.
Sep 15 12:04:01 vid systemd: Starting Session 208671 of user root.
Sep 15 12:04:01 vid systemd: Started Session 208670 of user root.
Sep 15 12:04:01 vid systemd: Starting Session 208670 of user root.
Sep 15 12:04:01 vid systemd: Started Session 208672 of user root.
Sep 15 12:04:01 vid systemd: Starting Session 208672 of user root.
......
..........
Sep 15 12:15:01 vid systemd: Starting Session 208707 of user root.
Sep 15 12:15:01 vid systemd: Started Session 208709 of user root.
Sep 15 12:15:01 vid systemd: Starting Session 208709 of user root.
Sep 15 12:15:01 vid systemd: Started Session 208708 of user root.
Sep 15 12:15:01 vid systemd: Starting Session 208708 of user root.
Sep 15 12:15:01 vid systemd: Created slice user-89.slice.
Sep 15 12:15:01 vid systemd: Starting user-89.slice.
Sep 15 12:15:01 vid systemd: Started Session 208710 of user vpopmail.
Sep 15 12:15:01 vid systemd: Starting Session 208710 of user vpopmail.
Sep 15 12:15:17 vid clamd: SelfCheck: Database status OK.
Sep 15 12:15:18 vid systemd: Removed slice user-89.slice.
Sep 15 12:15:18 vid systemd: Stopping user-89.slice.

Jeff


On 9/15/2017 4:09 PM, Eric Broch wrote:

Any entries in /var/log/mariadb/mariadb.log ?


On 9/15/2017 1:21 PM, Jeff Koch wrote:

For about a 15 minutes period users couldn't receive emails - emails were bouncing back saying the users did not exist. We traced the problem to the dovecot log where we saw this:

Sep 15 12:16:23 auth-worker: Error: vmysql: sql error[3]: Table 'vpopmail.users' doesn't exist Sep 15 12:16:23 auth-worker: Error: Attempting to rebuild connection to SQL server Sep 15 12:16:23 auth-worker: Error: vmysql: connection rebuild failed: Table 'vpopmail.users' doesn't exist

Shortly thereafter dovecot was able to connect and emails began being received normally again.

Any thoughts on how to prevent this in the future? Should we raise the number of mysql connections - we're using the default.

Regards, Jeff Koch

--
Eric Broch
White Horse Technical Consulting (WHTC)


--
Eric Broch
White Horse Technical Consulting (WHTC)




--
Eric Broch
White Horse Technical Consulting (WHTC)

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