Mysql with databases on HDD

[sbb]

Hi,

I need some help with using MySQL databases from Knoppix CD. There were some problems with my linux box because of which it has become unbootable. I am trying to salvage the data (some html/php files and MySQL databases). I can boot using Knoppix CD and can access all my data on hda3 after mounting it. I can even start mysqld both from /mnt/hda3/etc/init.d/ as well as /etc/init.d/. The problem is that both instances read only the databases in /var/lib while my databases are on /mnt/hda3/var/lib. If I do chroot, mysqld won't even start. If I move my database files into /var/lib/mysql from /mnt/hda3/var/lib/mysql, mysqld dies as soon as I start it. I tried changing the datadir in my.cnf but it didn't help.

All I want to do is backup (mysqldump) a couple of databases and move them over to a new host.

Could someone please help me out?

Thanks!

[Ambrose]

The mysql versions might be too different.

[markpreston]

Hi,

I need some help with using MySQL databases from Knoppix CD. There were some problems with my linux box because of which it has become unbootable. I am trying to salvage the data (some html/php files and MySQL databases). I can boot using Knoppix CD and can access all my data on hda3 after mounting it. I can even start mysqld both from /mnt/hda3/etc/init.d/ as well as /etc/init.d/. The problem is that both instances read only the databases in /var/lib while my databases are on /mnt/hda3/var/lib. If I do chroot, mysqld won't even start. If I move my database files into /var/lib/mysql from /mnt/hda3/var/lib/mysql, mysqld dies as soon as I start it. I tried changing the datadir in my.cnf but it didn't help.

All I want to do is backup (mysqldump) a couple of databases and move them over to a new host.

Could someone please help me out?

Thanks!

Could try something like this as root
rm -rf /var/lib/mysql
cp -rp /mnt/hda3/var/lib/mysql /var/lib
mysqld_safe &

then
# Back up data to USB device.

modprobe usb-storage
mkdir /mnt/usbstore
mount -t vfat /dev/sda1 /mnt/usbstore
mysqldump --opt -u root databasename > /mnt/usbstore/databasename.sql
umount /mnt/usbstore

Regards Mark

[gnarvaja]

All I want to do is backup (mysqldump) a couple of databases and move them over to a new host.

There are many ways of doing this:

a. The most obvious one is to copy the files from one server to the other
b. If you still want to do a mysqlump, there is a command line option to set the configuration file to use. In that configuratio file you can specify where the data files are
c. Make sure that the mysql.socket file is pointing to a rw location (that might have been your problem when it didn't start).
d. Start the MySQL server in 'console' mode.

Most of the time you should use a mysqld_safe script that does some housekeeping for you just in case. You can check all these options by using mysqld --help, the text will be version specific.

Check http://dev.mysql.com/doc/mysql/en/Upgrading-to-arch.html for some information in how copy databases between servers.
Check http://dev.mysql.com/doc/mysql/en/Starting_server.html as a starting point to troubleshooting.


The mysql versions might be too different.
The datafiles are backward and forward compatible, check

--GN