On Thursday 30 August 2001 14:09, Mustafa Hashmi wrote:
> Thanks for the response Joshua,
>
> That is an option - however not one I would be very comfortable with. I
> have a similar setup for virtual hosts generally - wanted something more
> flexible and powerful for a virtual server implementation without taxing
> the actual server too much.
>
> For example, the mail server (qmail) is not chrooted as such - however pop
> is chrooted via tcpserver, delivering messages to users in a virtual env.
> SMTP works the same way, chrooting to say "/home/user/etc/tcp.cdb" to check
> relay.
>
> Unfortunately, I know little about the actual "how-does-it-work" part of
> MySQL and need some direction :)
>
> I am going to try something in the next 3-4 days and hopefully I'll post a
> positive outcome.
>
> If this works, I'll write a HowTo :)
>
anti-Spam: database, query, SQL, MySQL
We run multiple instances of MySQL on the same machine. We use the ability
of the MySQL server to get its configuration from a file.
For instance, we have three instances on one machine that all run from
different directories.
We organize the directories like this:
instance1:
/...blah blah.../instance1/bin/ <--- special scripts for this instance
/...blah blah.../instance1/etc/ <--- config for this instance
/...blah blah.../instance1/log/ <--- logs for this instance
/...blah blah.../instance1/data/ <--- database data for this instance
/...blah blah.../instance1/run/ <-- PID file + socket for this instance
instance2:
/...blah blah.../instance2/bin/ <--- special scripts for this instance
/...blah blah.../instance2/etc/ <--- config for this instance
/...blah blah.../instance2/log/ <--- logs for this instance
/...blah blah.../instance2/data/ <--- database data for this instance
/...blah blah.../instance2/run/ <-- PID file + socket for this instance
etc....
In each etc/ directory for each instance, we have a my.cnf file that defines
all the data directories, socket files, log file paths etc. We also make
sure that each instance runs on a different port. This allows us to connect
to each instance remotely as well as locally. We use a base port address
(say 5000) and add the instance number. Thus instance one runs at port 5001,
instance two at 5002 etc.
Each instance is started by a special version of safe_mysqld (only very
mildly changed) that takes an extra argument. That argument is the instance
to run. It then adds the following to the command line for the mysqld binary:
/.../bin/mysqld --defaults-file=/...blah blah.../instanceX/etc/my.cnf
where X is the instance number and my.cnf is the specific config file for
that instance. We'd run it like this:
/...bin/mysql_ctrl instance1 start
We have also run MySQL in a completely chroot-ed environment where each
instance has its own copy of the MySQL binaries, libraries etc. This is
rather a pain to set up. MySQL does have some chroot capabilities of its
own, but we haven't tried them yet. There is some information in the online
manual if you look for it. The "native" MySQL chroot capabilities plus the
different config files sound more like what you want.
The fully chroot-ed environment lets us run different versions of MySQL
simultaneously. The different instances above require the same binary for
all instances. However, each instance can be controlled entirely separately
with different configurations, stopping and starting them independently etc.
One of the things that makes the instances very useful for us is that the
special scripts in the instance bin directories are hardcoded to use that
instance. Thus, we can just cd to the instance1/bin directory and use
scripts to bring up and down that instance without having to know what
instance it is. We were having problems with people forgetting which
instance they wanted to bring up or down and taking the wrong one down :-(
The hardcoded scripts stopped that error.
Best,
Kyle
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