mysql databases on separate drives

whysyn · 05-23-2006, 11:56 AM

Hi All!

Let me see if I can describe this so it makes sense...

I have a rather large database server. I'm setting up its replacement, and have run into a snag. On the old server, I had a drive with the OS on it, and individual drives per database. For example, /boot, /home, /var, all on sda partitions, and then sdb1, sdc1, and sdd1 mounted as /var/lib/mysql/database1/, /var/lib/mysql/database2/, /var/lib/mysql/database3/. This was great because each database gets hit hard and this spread the load across physical disks for increased performance. This was a RedHat 8 server running mysql 3.23.

The new system is running Fedora Core4 (x86_64) and mysql 4.1, but has a similar hard drive setup. Unfortunately, mysql 4.1 does not seem to like having separate drives for each database. Does anybody know of any config issues, or will the newer mysql version simply not support this? If I go into mysql and do a show databases, i only see "test" and "mysql," even though the directories also exist for database1, 2 & 3 and permissions are set correctly.

Thank you!

whysyn · 05-23-2006, 03:43 PM

OK, reading the docs, they suggest making a symlink for the directory, and mention nothing at all about mounting. Let's give it a whirl. I also have one database set up like this on the old server, so I know it should work. But of course it doesn't.

Can anybody help me make this work?

Brief summary again:
Fedora Core4, mySQL 4.1.16, x86_64
3 x database drives (no raid, one DB per drive)
1 x OS drive

I remounted the database drives as:

Code:

[root ~]# mount /dev/sdb1 /mnt/database1/
[root ~]# mount /dev/sdb1 /mnt/database2/
[root ~]# mount /dev/sdb1 /mnt/database3/

Double checked permissions & ownership... good to go.

I then made the symlinks:

Code:

[root ~]# ln -s /mnt/database1 /var/lib/mysql
[root ~]# ln -s /mnt/database2 /var/lib/mysql
[root ~]# ln -s /mnt/database3 /var/lib/mysql

And log into mysql:

Code:

mysql> show databases;
+----------+
| Database |
+----------+
| mysql    |
| test     |
+----------+
2 rows in set (0.01 sec)

Where are my databases?

Double checked the mysql directory:

Code:

[root ~]# cd ~mysql/
[root ~]# ls -l
total 20556
lrwxrwxrwx  1 root  root        12 May 23 16:39 database1 -> /mnt/database1
lrwxrwxrwx  1 root  root        12 May 23 16:39 database2 -> /mnt/database2
lrwxrwxrwx  1 root  root        12 May 23 16:39 database3 -> /mnt/database3
-rw-rw----  1 mysql mysql 10485760 May 23 16:38 ibdata1
-rw-rw----  1 mysql mysql  5242880 May 23 16:38 ib_logfile0
-rw-rw----  1 mysql mysql  5242880 Feb 22 13:36 ib_logfile1
drwxrwxr-x  2 mysql mysql     4096 May 23 11:39 mysql
srwxrwxrwx  1 mysql mysql        0 May 23 16:35 mysql.sock
drwxrwxr-x  2 mysql mysql     4096 Feb 22 13:36 test

ARGH!

whysyn · 05-24-2006, 03:25 PM

It seems this is a "problem" with SELinux.

I changed SELinux to "permissive" instead of "enforced" and mysql is now able to access databases on separately mounted drives.

Hopefully I'll be able to pull info out of the audit logs and reconfigure SELinux so I can have it in enforcement mode but still have mysql work properly...