Surviving the Migration: Strategies for High-Load MySQL Environments
Let’s be honest. Migrating a live production database is the systems administration equivalent of performing open-heart surgery while the patient is running a marathon. One wrong command, one missed flag, and you aren't just looking at downtime—you're looking at data corruption and a furious CEO screaming about lost revenue.
I've seen it happen. In 2012, a colleague tried to mysqldump a 50GB Magento database during peak hours. The table locks brought the site to a screeching halt. The load average hit 40. It wasn't pretty.
If you are still moving databases by shutting down the service and copying tarballs, you are doing it wrong. In the fast-paced Norwegian market, where users expect instant response times, downtime is a relic of the past. This guide covers how we move heavy workloads to CoolVDS infrastructure with near-zero downtime, ensuring compliance with Datatilsynet regulations.
The Bottleneck: It’s Always Disk I/O
Before we touch any config files, understand this: your migration speed is limited by your slowest disk. Most legacy VPS providers in Europe are still spinning rust (HDDs) or over-provisioned SATA SSDs. This is why we advocate for KVM-based virtualization.
Unlike OpenVZ, where a noisy neighbor can steal your IOPS, KVM guarantees resource isolation. When you deploy on CoolVDS, you get dedicated I/O throughput. This is critical during the restoration phase of a migration, where disk writes are the primary constraint.
The Tool: Percona XtraBackup
Forget mysqldump. For any dataset larger than 2GB, it is simply too slow and disruptive. We use Percona XtraBackup. It allows for hot backups of InnoDB tables without locking the database. Your site stays up. Your users keep buying.
1. Preparation
First, install the Percona repository on your old CentOS 6 server. Do not rely on default repositories; they are often outdated.
yum install http://www.percona.com/downloads/percona-release/percona-release-0.0-1.x86_64.rpm
yum install percona-xtrabackup-2.1
2. The Stream (Don't Waste Disk Space)
A rookie mistake is dumping the backup to the local disk first. If you have a 100GB database and only 20GB free space, you are stuck. Instead, we stream the backup directly to the new CoolVDS server using xbstream and SSH. This also secures the data in transit—essential for adhering to the Personal Data Act when moving customer data across networks.
innobackupex --user=root --password=YOURPASS --stream=xbstream /tmp | \
ssh root@new-coolvds-ip "xbstream -x -C /var/lib/mysql/backup/"
This command pipelines the backup. It reads from the old database and writes directly to the new server's SSD storage. No intermediate files.
The Cutover: Replication is Key
Once the base backup is restored on the new server, you aren't done. The old server has processed new transactions while you were moving data. You need to sync them.
We set up standard MySQL replication to catch up. This allows us to flip the switch whenever we want, with only seconds of downtime.
On the New Server (Slave):
# Check the xtrabackup_binlog_info file for coordinates
cat /var/lib/mysql/backup/xtrabackup_binlog_info
# Configure replication
mysql -e "CHANGE MASTER TO
MASTER_HOST='old-server-ip',
MASTER_USER='repl_user',
MASTER_PASSWORD='secure_password',
MASTER_LOG_FILE='mysql-bin.000001',
MASTER_LOG_POS=107;"
mysql -e "START SLAVE;"
Pro Tip: Ensure yourserver-idinmy.cnfis unique on both servers before starting. I once spent two hours debugging a replication loop because both servers had ID 1.
Optimizing for the New Hardware
You have moved to a CoolVDS high-performance instance. Don't run it with the default MySQL configuration. The defaults are designed for 512MB RAM, not the 16GB or 32GB beasts you can provision now.
Edit your /etc/my.cnf to leverage the SSD speeds and available RAM.
[mysqld]
# Allocate 70-80% of RAM to the pool
innodb_buffer_pool_size = 12G
# SSD Tuning: Increase I/O capacity
innodb_io_capacity = 2000
innodb_io_capacity_max = 4000
# Disable the doublewrite buffer if your filesystem/hardware guarantees atomic writes (Advanced)
# innodb_doublewrite = 0
# Transaction log settings
innodb_log_file_size = 512M
innodb_flush_log_at_trx_commit = 2 # Slight risk, massive speed gainSetting innodb_io_capacity to 2000 tells MySQL, "Hey, we aren't on a slow 7200RPM drive anymore. Push it." This is where the CoolVDS infrastructure shines. We use high-grade enterprise SSDs that eat these IOPS for breakfast.
Network Latency and Sovereignty
Why host in Norway? Latency and Law. If your customers are in Oslo or Bergen, hosting in a datacenter in Texas is madness. The speed of light is a hard limit. Pinging a server in the US takes ~120ms. Pinging a server connected to NIX (Norwegian Internet Exchange) takes ~2-10ms.
Furthermore, with the Data Protection Directive (95/46/EC) and strict enforcement by Datatilsynet, keeping personal data within Norwegian borders simplifies your legal compliance significantly. You don't want to explain to an auditor why your customer database is sitting on a server subject to the US Patriot Act.
Final Thoughts
Migration isn't just about moving files. It's about maintaining trust. Trust that the site stays up. Trust that the data is safe. Trust that the new server can handle the load.
By combining tools like Percona XtraBackup with the raw power of KVM-virtualized SSD instances, you eliminate the risks associated with legacy hosting. Don't let your infrastructure become your bottleneck.
Ready to upgrade? Spin up a high-performance CoolVDS instance in 55 seconds and test these I/O speeds yourself.