Moving 20 big servers (with over 200 virtual machines) from one data center to another is not an easy task, and for our customers this meant a downtime of some hours for all our web services.
To keep our customers informed during the downtime we chose to leave a small server that in the old data center would listen on all our IPs and serve a static maintenance page.
So we did the following:
- get a Raspberry Pi (fortunately we already had one)
- install the latest Raspbian
- add all our IP addresses to its network interface
- have nginx deliver one simple page (with some CSS and images) at any URL
- disable all access logging, PHP, etc.
- connect it to the internet upstream
And it performed very well during the move:
- uptime: 12 hours
- HTTP connections: > 9 million (~ 208/sec)
- HTTP requests: > 20 million (~ 462/sec)
- avg. packet size: 130 bytes (recv), 260 bytes (sent)
- avg. concurrent connections: 10,000
- total traffic: 51.4 GiB (17.5 GiB recv, 33.9 GiB sent)
- system load avg: 1-2 (2 nginx workers)
- CPU load: between 70% and 90%
Thanks to Mark for the statistics.