Hello, i´m having a problem and i would like to know if anyone can help me.
Three days ago my site went dead. I restored a backup from the day before and i got the message "error establishing a database connection".
I tried to restore a backup from the week before, i got the same error message.
I then restored a backup from a snapshot i took 2 months ago, same message!
Isn´t that strange?

* I upgraded KVM and it´s shown as idle (don´t know if this is correct)

** I tried to do a "sudo apt-get upgrade" and i get the mysql error message bellow:

dpkg: error processing mysql-server-               5.5 (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of mysql-server:
 mysql-server depends on mysql-server-5.5; however:
  Package mysql-server-5.5 is not configured yet.
dpkg: error processing mysql-server (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 mysql-server-5.5
 mysql-server
E: Sub-process /usr/bin/dpkg returned an error code (1)

*** Why my old backups don´t fix the problem? The site went down just three days ago.

**** My setup is a LAMP - Ubuntu 12.04 LTS

Do you have multiple servers, or a single one? Is your database stored locally, or elsewhere?

Just one server and the database is stored locally.

I think you didn´t read my explanation, my site was working fine, it just stopped suddenly. But what i think is weird is that all my backups are not working.
Any help?

That last message was spam, there's been a lot of that lately.

Sounds like your database is corrupt in the backups which isn't unusual since the backups take file snapshots so the database can be mid-write while it's backing up. You should run mysqldump or something similar before a backup runs and restore that if this happens.

If you don't have a dump file to restore, check the mysql log file which most likely is either in /var/log, /var/log/mysql, /var/lib/mysql or the entries are in /var/log/syslog or /var/log/messages

The log should say exactly what's wrong, post the contents here.

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Thanks obs for any help.
I try to do a mysqldump but i´m getting thir error message:

Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) when trying to connect

I figured out i don´t have a mysqld.sock in the /run/mysqld/ directory, is this normal?

Take my advice with a grain of salt- I'm a meatball Linux guy, and have broken more than my fair share, but because of the dpkg error, I would try :
sudo dpkg --configure -a
or
sudo apt-get -f install.

_________________
--
Chris Bryant

Hi Chris, thank you for your help, i tried sudo dpkg --configure -a
I got this:

Setting up mysql-server-5.5 (5.5.43-0ubuntu0.12.04.1) ...
start: Job failed to start
invoke-rc.d: initscript mysql, action "start" failed.
dpkg: error processing mysql-server-5.5 (--configure):
 subprocess installed post-installation script returned error exit status 1
dpkg: dependency problems prevent configuration of mysql-server:
 mysql-server depends on mysql-server-5.5; however:
  Package mysql-server-5.5 is not configured yet.
dpkg: error processing mysql-server (--configure):
 dependency problems - leaving unconfigured
Errors were encountered while processing:
 mysql-server-5.5
 mysql-server

Check my comment about log files, the lack of a mysql.sock just means mysql isn't running you need to find out why it's not running and the logs will tell you that.

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Do you think these logs can give me a clue?

/var/log/mysql/error.log

150720 11:37:51 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
150720 11:37:51 [Note] Plugin 'FEDERATED' is disabled.
/usr/sbin/mysqld: Incorrect file format 'plugin'
150720 11:37:51 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
150720 11:37:51 InnoDB: The InnoDB memory heap is disabled
150720 11:37:51 InnoDB: Mutexes and rw_locks use GCC atomic builtins
150720 11:37:51 InnoDB: Compressed tables use zlib 1.2.3.4
150720 11:37:51 InnoDB: Initializing buffer pool, size = 128.0M
150720 11:37:51 InnoDB: Completed initialization of buffer pool
150720 11:37:51 InnoDB: highest supported file format is Barracuda.
150720 11:37:51  InnoDB: Waiting for the background threads to start
150720 11:37:52 InnoDB: 5.5.43 started; log sequence number 4919996271
150720 11:37:52 [Note] Server hostname (bind-address): '127.0.0.1'; port: 3306
150720 11:37:52 [Note]   - '127.0.0.1' resolves to '127.0.0.1';
150720 11:37:52 [Note] Server socket created on IP: '127.0.0.1'.
150720 11:37:52 [ERROR] Fatal error: Can't open and lock privilege tables: Incorrect file format 'host'

/var/log/syslog

...
Jul 20 11:37:51 myname postfix/master[3281]: daemon started -- version 2.9.6, configuration /etc/postfix
Jul 20 11:37:51 myname ntpd[3310]: ntpd 4.2.6p3@1.2290-o Mon Apr 13 13:41:45 UTC 2015 (1)
Jul 20 11:37:51 myname ntpd[3311]: proto: precision = 0.347 usec
Jul 20 11:37:51 myname ntpd[3311]: ntp_io: estimated max descriptors: 1024, initial socket boundary: 16
Jul 20 11:37:51 myname ntpd[3311]: unable to bind to wildcard address 0.0.0.0 - another process may be running - EXITING
Jul 20 11:37:52 myname kernel: init: mysql main process (3131) terminated with status 1
Jul 20 11:37:52 myname kernel: init: mysql main process ended, respawning
Jul 20 11:37:53 myname kernel: init: mysql post-start process (3132) terminated with status 1
Jul 20 11:37:54 myname kernel: init: mysql main process (3447) terminated with status 1
Jul 20 11:37:54 myname kernel: init: mysql main process ended, respawning
Jul 20 11:37:55 myname kernel: init: mysql post-start process (3448) terminated with status 1
Jul 20 11:37:56 myname kernel: init: mysql main process (3512) terminated with status 1
Jul 20 11:37:56 myname kernel: init: mysql main process ended, respawning
Jul 20 11:37:57 myname kernel: init: mysql post-start process (3513) terminated with status 1
Jul 20 11:37:58 myname kernel: init: mysql main process (3575) terminated with status 1
Jul 20 11:37:58 myname kernel: init: mysql respawning too fast, stopped
Jul 20 11:38:02 myname ntpdate[3038]: adjust time server 129.6.15.29 offset 0.145989 sec
Jul 20 11:38:02 myname ntpd[3646]: ntpd 4.2.6p3@1.2290-o Mon Apr 13 13:41:45 UTC 2015 (1)
Jul 20 11:38:02 myname ntpd[3647]: proto: precision = 0.344 usec
Jul 20 11:38:02 myname ntpd[3647]: ntp_io: estimated max descriptors: 1024, initial socket boundary: 16
Jul 20 11:38:02 myname ntpd[3647]: Listen and drop on 0 v4wildcard 0.0.0.0 UDP 123
Jul 20 11:38:02 myname ntpd[3647]: Listen and drop on 1 v6wildcard :: UDP 123
Jul 20 11:38:02 myname ntpd[3647]: Listen normally on 2 lo 127.0.0.1 UDP 123
Jul 20 11:38:02 myname ntpd[3647]: Listen normally on 3 eth0 198.74.52.6 UDP 123
Jul 20 11:38:02 myname ntpd[3647]: Listen normally on 4 lo ::1 UDP 123
Jul 20 11:38:02 myname ntpd[3647]: Listen normally on 5 eth0 fe80::f03c:91ff:fe6e:860 UDP 123
Jul 20 11:38:02 myname ntpd[3647]: Listen normally on 6 eth0 2600:3c02::f03c:91ff:fe6e:860 UDP 123
Jul 20 11:38:02 myname ntpd[3647]: peers refreshed
Jul 20 11:38:02 myname ntpd[3647]: Listening on routing socket on fd #23 for interface updates
Jul 20 11:39:01 myname CRON[3652]: (root) CMD (  [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete)
Jul 20 11:42:27 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=162.248.10.134 DST=198.74.52.6 LEN=44 TOS=0x00 PREC=0x00 TTL=48 ID=63161 PROTO=TCP SPT=54420 DPT=22 WINDOW=4096 RES=0x00 SYN URGP=0 
Jul 20 11:42:27 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=162.248.10.134 DST=198.74.52.6 LEN=44 TOS=0x00 PREC=0x00 TTL=49 ID=3843 PROTO=TCP SPT=54421 DPT=22 WINDOW=1024 RES=0x00 SYN URGP=0 
Jul 20 11:45:01 myname CRON[3929]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)
Jul 20 11:45:30 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=186.227.209.122 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=120 ID=33346 DF PROTO=TCP SPT=2939 DPT=445 WINDOW=65535 RES=0x00 SYN URGP=0 
Jul 20 11:45:33 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=186.227.209.122 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=120 ID=33669 DF PROTO=TCP SPT=2939 DPT=445 WINDOW=65535 RES=0x00 SYN URGP=0 
Jul 20 11:49:05 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:41:08:00 SRC=162.252.86.85 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=56 ID=42322 PROTO=UDP SPT=5043 DPT=33434 LEN=28 
Jul 20 11:49:05 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=68.233.224.4 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=59 ID=42323 PROTO=UDP SPT=16292 DPT=33434 LEN=28 
Jul 20 11:49:05 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:41:08:00 SRC=104.156.63.21 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=55 ID=42324 PROTO=UDP SPT=51234 DPT=33434 LEN=28 
Jul 20 11:49:05 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=162.252.86.83 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=57 ID=42328 PROTO=UDP SPT=7911 DPT=33434 LEN=28 
Jul 20 11:49:05 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:41:08:00 SRC=104.156.63.21 DST=198.74.52.6 LEN=40 TOS=0x00 PREC=0x00 TTL=55 ID=42327 PROTO=TCP SPT=51249 DPT=33434 WINDOW=5840 RES=0x00 SYN URGP=0 
Jul 20 11:50:17 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=217.116.128.15 DST=198.74.52.6 LEN=40 TOS=0x00 PREC=0x00 TTL=119 ID=256 DF PROTO=TCP SPT=12200 DPT=5900 WINDOW=8192 RES=0x00 SYN URGP=0 
Jul 20 11:51:41 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:41:08:00 SRC=45.35.26.34 DST=198.74.52.6 LEN=40 TOS=0x00 PREC=0x00 TTL=109 ID=256 PROTO=TCP SPT=6000 DPT=3306 WINDOW=16384 RES=0x00 SYN URGP=0 
Jul 20 11:51:56 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=128.71.123.78 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=119 ID=36060 DF PROTO=TCP SPT=3930 DPT=445 WINDOW=65535 RES=0x00 SYN URGP=0 
Jul 20 11:51:59 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=128.71.123.78 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=119 ID=36916 DF PROTO=TCP SPT=3930 DPT=445 WINDOW=65535 RES=0x00 SYN URGP=0 
Jul 20 11:55:01 myname CRON[4067]: (root) CMD (command -v debian-sa1 > /dev/null && debian-sa1 1 1)

Looks like your database is a bit knackered. First backup the mysql directory tar -cvpf /root/mysql.tar /var/lib/mysql then try running mysql_upgrade && service mysql start

See if that helps

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Hi obs, thank you for helping, i did the backup.
When trying to run "mysql_upgrade && service mysql start", i get:

Looking for 'mysql' as: mysql
Looking for 'mysqlcheck' as: mysqlcheck
FATAL ERROR: Upgrade failed

What do the logs say after you ran mysql_upgrade?

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How to ask for help
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/var/log/syslog:

Jul 21 15:37:13 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=85.97.107.120 DST=198.74.52.6 LEN=60 TOS=0x00 PREC=0x00 TTL=54 ID=50473 DF PROTO=TCP SPT=50741 DPT=23 WINDOW=5808 RES=0x00 SYN URGP=0 
Jul 21 15:37:16 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=85.97.107.120 DST=198.74.52.6 LEN=60 TOS=0x00 PREC=0x00 TTL=54 ID=50474 DF PROTO=TCP SPT=50741 DPT=23 WINDOW=5808 RES=0x00 SYN URGP=0 
Jul 21 15:37:22 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=85.97.107.120 DST=198.74.52.6 LEN=60 TOS=0x00 PREC=0x00 TTL=54 ID=50475 DF PROTO=TCP SPT=50741 DPT=23 WINDOW=5808 RES=0x00 SYN URGP=0 
Jul 21 15:37:37 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=80.72.77.137 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=116 ID=22695 DF PROTO=TCP SPT=29294 DPT=445 WINDOW=65535 RES=0x00 SYN URGP=0 
Jul 21 15:37:40 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=80.72.77.137 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=116 ID=23275 DF PROTO=TCP SPT=29294 DPT=445 WINDOW=65535 RES=0x00 SYN URGP=0 
Jul 21 15:38:58 myname kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:41:08:00 SRC=178.32.43.113 DST=198.74.52.6 LEN=44 TOS=0x00 PREC=0x00 TTL=50 ID=61092 PROTO=TCP SPT=80 DPT=20287 WINDOW=16384 RES=0x00 ACK SYN URGP=0 
Jul 21 15:39:01 myname CRON[6349]: (root) CMD (  [ -x /usr/lib/php5/maxlifetime ] && [ -d /var/lib/php5 ] && find /var/lib/php5/ -depth -mindepth 1 -maxdepth 1 -type f -cmin +$(/usr/lib/php5/maxlifetime) ! -execdir fuser -s {} 2>/dev/null \; -delete)
Jul 21 15:40:39 myname  kernel: iptables denied: IN=eth0 OUT= MAC=f2:3c:91:6e:08:60:84:78:ac:5a:19:c1:08:00 SRC=115.248.191.9 DST=198.74.52.6 LEN=48 TOS=0x00 PREC=0x00 TTL=120 ID=3889 PROTO=TCP SPT=59586 DPT=22 WINDOW=65535 RES=0x00 SYN URGP=0 

/var/log/mysql/error.log:
BLANK!

Hrm well it's knackered and without poking around there's not much else I can do if there's no extra log info. This is why running dumps before a backup is recommended in the backup docs. You could try running mysql_install_db if you're lucky only the mysql internal tables are corrupt and that will create new ones which may allow mysql to start.

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How to ask for help
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