Greg Swift wrote:
> Dallas L. Engelken wrote:
>>> -----Original Message-----
>>> From: ISP Lists [mailto:[EMAIL PROTECTED]
>>> Sent: Wednesday, August 24, 2005 10:21 AM
>>> To: vchkpw@inter7.com
>>> Subject: Re: [vchkpw] Spotty behavior authenticating: MySQL server
>>> has gone away 
>>> 
>>> 
>>>> Something peculiar happened to mysql during a reboot and
>>>> 
>>> now vpopmail
>>> 
>>>> authdaemond is having trouble completing authentications....
>>>> 
>>>> /var/log/maillog says:
>>>> 
>>>> Aug 24 08:36:15 hostname authdaemond: vmysql: sql error[3]: MySQL
>>>> server has gone away 
>>>> 
>>>> 
>>>> This problem is spotty though.  I have several successful
>>>> authentications before this error occurs.  I then have to restart
>>>> mysqld before I can get any other authentications to succeed.  I am
>>>> still able to use the mysql client to connect to the server
>>>> 
>>> for an interactive session.
>>> 
>>>> What seems strange to me is that there are only two mysql
>>>> 
>>> daemons running:
>>> 
>>>> root     23923  0.0  0.1  5060 1108 pts/0    S    09:13
>>>> 
>>> 0:00 /bin/sh
>>> 
>>>> /usr/bin/safe_mysqld --defaults-file=/etc/my.cnf
>>>> --pid-file=/var/run/mysqld/mysqld.pid
>>>> 
>>>> mysql    23956  0.0  0.5 38620 5656 pts/0    Sl   09:13   0:00
>>>> /usr/libexec/mysqld --defaults-file=/etc/my.cnf --basedir=/var/lib
>>>> --datadir=/var/lib/mysql --user=mysql
>>>> --pid-file=/var/run/mysqld/mysqld.pid --skip-locking
>>>> 
>>>> 
>>>> Every other instance of mysql 3.23.x I've ever run has
>>>> 
>>> about 10 child
>>> 
>>>> threads running, so this seems strange to see only one child
>>>> thread. 
>>>> 
>>>> I have not updated any packages on this box recently.  None
>>>> 
>>> at all, I
>>> 
>>>> swear.
>>>> 
>>>> Suggestions to investigate?  Googling on the "MySQL server
>>>> 
>>> has gone away"
>>> 
>>>> is a wild goose chase.
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> 
>>> Hrm, rebooting the box seems to have helped.  Still same
>>> number of mysql daemons, but they're answering now...  Damned
>>> strange.  dmesg on reboot didn't show any ext3 errors being
>>> fixed - I was wondering if this was a disk thing.
>>> 
>>> Thoughts still welcome and appreciated on this.
>>> 
> Well.. just for reference (cause it took me a while to figure this one
> out)... if your box is running with multiple name servers configured
> for resolution, and the primary stops responding, you will see this
> same issue.  What happens is the slight delay added to the auth
> sequence as the mysql fails to the secondary resolver causes the
> vpopmail to fail the connection.
> 
> 
> To be more specific this will occur:
> 
> 1: primary name server fails
> 2: When authentication to DB it takes a longer time due to system
> having to fail to secondary resolver.
> 3: vpopmail's auth to db starts failing due to timeouts (mysql takes
> to long to respond, but does respond), vpopmail tries harder to
> connect to db, connection count sky rockets (I saw upwards of 1400
> connections) and in turn the connections do not close properly.
> 4: db locks up hard.
> 5: once you quiet down vpopmail (easiest way was to disable incoming
> access sadly), test messages show that an occasional message wil lgo
> through, but the rest receive the "MySQL server has gone away"
> message. 
> 6. Trying to auth to db, albeit slightly slower than normal, responds
> and allows auth.  Once in runs perfectly.
> 7. You realize that its primary dns server is off for whatever reason,
> start it, and voila no problem.
> 
> 
> Now admittedly, previously I've seen the same thing but for other
> reasons, this was just the more obscure annoying one.
> 
> Yes I realize that a local dns server make a lot of sense for this
> situation, but if the named on that box stops, and it has your other
> name servers as secondary, WHEN are you gonna realize that?  Most
> people would not add that to their monitoring.  LOTS of fun.
> 
> -Greg

Or, I would think, you could just add the server/client to the hosts file(s)
and skip DNS entirely. Or use IP addresses.


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