7.5.1. System Factors and Startup Parameter Tuning
We start with system-level factors, because some of these
decisions must be made very early to achieve large performance
gains. In other cases, a quick look at this section may suffice.
However, it is always nice to have a sense of how much can be
gained by changing factors that apply at this level.
The operating system to use is very important. To get the best
use of multiple-CPU machines, you should use Solaris (because
its threads implementation works well) or Linux (because the 2.4
and later kernels have good SMP support). Note that older Linux
kernels have a 2GB filesize limit by default. If you have such a
kernel and a need for files larger than 2GB, you should get the
Large File Support (LFS) patch for the ext2 filesystem. Other
filesystems such as ReiserFS and XFS do not have this 2GB
limitation.
Before using MySQL in production, we advise you to test it on
your intended platform.
Other tips:
If you have enough RAM, you could remove all swap devices.
Some operating systems use a swap device in some contexts
even if you have free memory.
-
Avoid external locking. Since MySQL 4.0, the default has
been for external locking to be disabled on all systems. The
--external-locking and
--skip-external-locking options explicitly
enable and disable external locking.
Note that disabling external locking does not affect MySQL's
functionality as long as you run only one server. Just
remember to take down the server (or lock and flush the
relevant tables) before you run
myisamchk. On some systems it is
mandatory to disable external locking because it does not
work, anyway.
The only case in which you cannot disable external locking
is when you run multiple MySQL servers
(not clients) on the same data, or if you run
myisamchk to check (not repair) a table
without telling the server to flush and lock the tables
first. Note that using multiple MySQL servers to access the
same data concurrently is generally not
recommended, except when using MySQL Cluster.
The LOCK TABLES and UNLOCK
TABLES statements use internal locking, so you can
use them even if external locking is disabled.
