Databases, Systems & Networks

Sometimes we need to migrate our databases to a new MySQL server.  It is easy to move the databases, but without the users and their permissions, our new databases would be worthless.  Below is a step-by-step on migrating MySQL users to a new MySQL server

Step 1 – Create a Query List That We Can Use to Get Grants for All Users

I use these options so that I wouldn’t get any formatting characters that I would have to manually delete later.

• -N skip column names in the output
• -p password – Asks me to type the password so nobody can get it from the command line history
• -s  silent mode – less formatting output that we don’t want like “|” and “-“

So, let’s get a list of the users in a query that we can use to get the grants.  Our query will be output into the “myfile” file

$ mysql -uroot -N -p -s > myfile
Enter password:
select Distinct CONCAT(‘show grants for `’, user, ‘`@`’, host, ‘`;’) as query from mysql.user;
quit

If we want to see what our query file look like, we can take a quick peek:

[root@classes-dev-mysql ~]# cat myfile
show grants for `user1`@`%`;
show grants for `user2`@`%`;
show grants for `user3`@`10.%`;
show grants for `user4`@`10.%`;
show grants for `jeff`@`10.%`;

Step 2 – Create the MySQL Grant File

We don’t have quite what we want and need yet.  We are looking for a query that will create all of our users on the new MySQL server.  We need to run the query that we just created and it will give us the query that we will use later to create the users.  It will create our grant permission statements in a file named “grantfile”

[root@classes-dev-mysql ~]# mysql -uroot -N -p -s -r < myfile > grantfile
Enter password:

We can take a peek at what our grantfile contains:

$ cat grantfile
GRANT USAGE ON *.* TO ‘user1’@’%’ IDENTIFIED BY PASSWORD ‘5ea9af6g6t27032f’
GRANT ALL PRIVILEGES ON `database1`.* TO ‘user1’@’%’
GRANT USAGE ON *.* TO ‘user2’@’10.%’ IDENTIFIED BY PASSWORD ‘2a123b405cbfe27d’
GRANT SELECT ON `database1`.`table1` TO ‘user2’@’10.%’GRANT ALL PRIVILEGES ON *.* TO ‘user3’@’10.%’ IDENTIFIED BY PASSWORD ‘753af2za1be637ea’
GRANT SELECT, INSERT, UPDATE, DELETE ON *.* TO ‘user3’@’10.%’ IDENTIFIED BY PASSWORD ’08ad9be605rfgcb’…

Step 3 – Create Users and Grant MySQL Permissions on the New MySQL Machine

Now we are done working on the source machine.  We need to copy our file named “grantfile” over to the new machine.

$ scp grantfile myuser@mysql2.uptimemadeeasy.com:/home/myuser

Next, we login to the destination or the new MySQL machine that we are building and run the “grantfile” in MySQL to create our users on the new MySQL machine.

$ mysql -uroot -p < ./grantfile

That’s it.  As long as our databases are named the same in the new MySQL, our users should be ready to use the copy of the databases in the new MySQL machine.

Source: Uptime Made Easy

What is the main objective of this entire topology?

Redundancy and Load Sharing! Imagine a scenario where your single web server is receiving millions and millions of HTTP requests per second, the CPU load is going insane, as well as the memory usage, when suddenly “crash!”, the server dies without saying good-bye (probably because of some weird hardware out-stage that you certainly won’t have time to debug). Well, this simple scheme might lead you into a brand new world of possibilities

#vi /etc/hosts
192.168.0.241   haproxy
192.168.0.39    Node1
192.168.0.30    Node2
192.168.223.147 Node1
192.168.223.148 Node2
192.168.0.58    Web1
192.168.0.139   Web2
192.168.0.132   Mysql

Lire la suite…

How to set-up a high-availability cluster

Here are a few notes about how to set-up a high-availability web server farm using Ubuntu 12.04 LTS using a whole load of awesome software (HAProxy, HeartBeat, Watchdog and Nginx)

The setup

In my setup I have five virtual machines, these are named and used for the following:-

haproxy1 – Our first proxy (master)/load-balancer (running HAProxy, HeartBeat and Watchdog) [IP address: 172.25.87.190]
haproxy2 – Our second proxy (failover)/load-balancer (running HAProxy, HeartBeat and Watchdog) [IP address: 172.25.87.191]
web1 – Our first web server node (running nginx) [IP address: 172.25.87.192]
web2 – Our second web server node (running nginx) [IP address: 172.25.87.193]
web3 – Our third web server node (running nginx) [IP address: 172.25.87.194]

The servers are connected in the following way:-

In my next post I will also explain how to configure the web servers to point to a backend shared storage cluster (using NFS) and a MySQL cluster server to have a truly highly available web hosting platform.

Lire la suite…

In this tutorial, I’ll show you the steps to create a simple failover cluster on Ubuntu using CARP. To make the things meaningful,we’ll create the cluster for Apache service but you can use it for any other service, which relay on IP.

Scenario:

Here is my Setup:

PrimarySrv: This is the main server, where I configured the apache and which act as Master (IP: 192.168.1.202)
SecondarySrv: 2nd Apache Server where I configured the apache exactly like on PrimarySrv (IP : 192.168.1.203)
192.168.1.250 : Virtual IP address,created using Ucarp.

Ucarp is really simple, it works like this,when the PrimarySrv is up,it will assign the virtual IP 192.168.1.250 to it, in case that PrimarySrv is down then it will assign virtual IP to the SeconadrySrv and when the PrimarySrv will come online, it will assign the virtual IP once again to it.

Lire la suite…