Detailed info
Clustering Technology
Each cluster contains two identical dedicated physical servers interconnected with a separate Gigabit line providing online drive synchronization. Both physical servers together constitute a virtual shared storage available for both of the servers and all data is simultaneously written in both of servers. All data reads are local, though, so the reading speed and latency does not differ from a standalone server solution.
For every cluster there is a primary server, which serves the web content and provides other services, and a hot standby, which is ready to mount the shared storage any time should the primary server fail. In this case, the hot standby server will become the new primary within a minute. Once the previous primary is revived, it becomes the new hot standby (since the servers are identical, there is no point to switch servers back).
Availability is constantly monitored from inside and outside by cloud-based systems, so the administrators are notified in case of any problems at once.
Data center
Our cluster servers are located in a newly built well-maintained and ventilated data center in ex-VEF territory in Riga, Latvia.
It has independent power lines from two different 1.2MW transformers connected to a recently reconstructed strategic Latvenergo power substation, which feeds Brivibas street and the Cabinet of Ministers of Latvia. The substation itself was build with redundancy in mind and provides one of the most stable electricity supplies in the Republic of Latvia. The power lines are connected to a UPS array that is capable to sustain the datacenter for about half an hour if neither power lines are available.
There are two independent fiber links to Latvian Internet exchange centers LIX and SMILE and to the backbone operator Baltcom IP. In case of failure, backup link is activated in less than a minute.
Hardware
The servers are built using high quality components. Each has at least Intel Core2Quad Q6600 2.4GHz processor and at least 8GB of RAM. The storage system consists of 4 1TB drives configured as a battery-backed hardware RAID10 array.
Shared Hosting
Our system currently has two cPanel servers - secure1.serveriem.lv (phpinfo) and secure2.serveriem.lv (phpinfo) with the following software:
- 64bit CentOS 5.5 with Linux 2.6.32;
- dynamic content is served by Apache 2.2.17 with FastCGI and ionCube Loader;
- static content is served by Nginx 1.0 working as a reverse-proxy for the Apache server;
- PHP 5.3.6, Perl 5.8.8, Python 2.4.3, TCL/TK 8.4.13, Ruby 1.8.7;
- MySQL 5.1.56, PgSQL 8.1.22, SQLite 3.3.6;
- Softaculous 3.2.
NB: our systems are updated on a regular basis, so software versions listed here may be older than actual software installed.
DNS service is provided by a DNS cluster consisting of three different nameservers: ns1.serveriem.lv (Latvia), ns2.serveriem.lv (Latvia) and ns3.serveriem.lv (UK). The servers are fully synchronised and all records are identical.
cPanel servers perform daily backups. The latest daily backup and the latest weekly backup are kept. The backups are stored both locally and on an off-site storage server (in Latvia).
Virtual Servers
All Virtual Servers benefit from the High Availability infrastructure developed by Serveriem.LV. We use OpenVZ as our platform of choice as it provides best performance in all areas compared to other virtualization platforms. Unfortunately, due to OpenVZ limitations, all Virtual Servers use the same kernel, so it is not possible to install custom kernel or kernel modules.
We provide our virtual machines preinstalled with one of the following systems (few different versions are possible): Alt Linux, Arch Linux, CentOS, Debian, Fedora, Slackware, SuSE, Ubuntu Server.
Upon request we can provide a DNS hosting account also for Virtual Server users, so that they could benefit from our redundant DNS system.
No backups are made for Virtual Servers automatically, so it is up to the users to perform and keep backups. The servers are kept, however, on our RAID10 storage synchronised between two independent systems, so the probability of data loss is extremely low.