Make sure to use the –databases option when backing up single MySQL databases

Targeting a single database with these options:

mysqldump -u MY_DB_BACKUP_USER -p MY_DB_NAME --add-drop-table --add-drop-database > my_db_name_mmddyyyy.sql

will successfully backup the database, but if you were to restore the database backup file back into a database with a newer schema (additional tables for example) like so:

mysql -u my_db_access_user -p MY_DB_NAME < my_db_name_mmddyyyy.sql

you would end up with a “merged” version of the database that would have new tables from the more recent schema and restored tables from the backup:

I learned this the hard way recently when attempting to restore a database to an earlier version following a failed Redmine 3.0.2 upgrade. While this didn’t break anything (other than maybe a future upgrade attempt that doesn’t properly handle existing tables), it wasn’t what I intended.

Going forward, if I want to backup a single database and have the backup file contain the statement necessary to first drop the database before restoring it (a full restore for example), I’ll need to call the mysqlbackup command like so:

mysqldump -u MY_DB_BACKUP_USER -p --databases MY_DB_NAME --add-drop-table --add-drop-database > my_db_name_mmddyyyy.sql

Note the --databases statement. If you didn’t know this, I hope it helps you from making the same mistake.

mount error (13): Permission denied

Running into cryptic errors really sucks, and this was certainly no exception. We had a Windows share provided to us that we wanted to mount to an Ubuntu 10.04 LTS server for general storage.

After reading the Ubuntu MountWindowsSharesPermanently wiki page and consulting the smbmount man page I came up with this new (initial) /etc/fstab entry:

//192.168.1.5/test-smb1 /mnt/it_hosted cifs credentials=/root/it_hosted_windows_share_mount.conf,iocharset=utf8,sec=ntlm2 0 0

The /root/it_hosted_windows_share_mount.conf file contained:

username=storageuser
password=SuperSecret
domain=example

I’ve substituted values of course. One thing to note is that if example.com were the real domain, I’ve made sure to use example as the value.

Then came the mount error (13): Permission denied error. I tried from a Windows box and was able to connect fine, so I knew that the server/share wasn’t the problem.

I then decided to call mount directly as shown here. After getting that working, I rechecked the syntax used in /etc/fstab and then finally looked at /root/it_hosted_windows_share_mount.conf again.

What do you know, the old & much despised EOL issue. After changing the DOS EOL to UNIX everything worked. I can’t count the number of times I’ve been bitten by that.