MySQL

mysqldump returning Errcode 13

Last tested on Ubuntu 14.04.2 LTS (trusty)

When I try to create a CSV file from a table in the database I'd get an Errcode 13. Here I'm trying to extract a table called enc_codes3 from a database called testdb

mhan@dbserver:~$ mysqldump --tab=./testdump -uroot -p --fields-terminated-by=, --fields-enclosed-by='"' --lines-terminated-by=0x0d0a -t testdb enc_codes3
Enter password:
mysqldump: Got error: 1: Can't create/write to file '/home/mhan/testdump/enc_codes3.txt' (Errcode: 13) when executing 'SELECT INTO OUTFILE'

Make sure that the mysql daemon (mysql:mysql on Ubuntu) is able to write to the folder.

apparmor status can be checked via sudo aa-status.

Disable apparmor temporary ( service apparmor teardown ) execute the above command and then restart it again ( service apparmor start ).

Moving all of the databases from one server to another

Last tested on Ubuntu 16.04.01 LTS (xenial)

Log in as an admin on MySQL Console and lock the database to allow only read operations.

mysql> flush tables with read lock;
mysql> set global read_only = on;
mysql> exit

Dump all of the databases into a file.

$ mysqldump --lock-all-tables -u root -p --all-databases > dbs.sql

Copy the dump to the new server. RSYNC is preferred over SCP, especially if the file is large.

$ rsync -tvz --progress dbs.sql mhan@newserver.com:~/files/
or
$ scp dbs.sql mhan@newserver.com:~/files/

The DB can be (optionally) unlocked. This may or may not be a good thing to do in your case. Do it at your own risk.

mysql> set global read_only = off;
mysql> unlock tables;
mysql> exit

On the new server, execute this command to import the new SQL dump.

$ mysql -u root -p < ~/files/dbs.sql

IMPORTANT: If your file is large, or you just have a lot of records, you may want to make sure you have something bigger than 16M for max_allowed_packet attribute in your my.cnf (usually found under /etc/mysql/ or /etc/mysql/mysql.conf.d/) on your new server where you're doing the import, else the server could hang on a large insert operation and your MySQL server may actually decide to go away, literally. On one of the servers I had it for 1024M just for this operation and brought it back low afterwards.