What are some alternatives?
When comparing ReadyNAS and PetaSAN, you can also consider the following products
FreeNAS - FreeNAS is a storage operating system strong and robust enough to meet the needs of enterprise level businesses.
OpenMediaVault - OpenMediaVault is the next generation network attached storage (NAS) solution based on Debian Linux.
Rockstor - Rockstor is a free and open source NAS (Network Attached Storage) operating system.
Amahi Home Server - Amahi is a media, home and app server software known for its easy-to-use user interface. Amahi has the best media, backup and web apps for small networks.
Unraid - Simplicity. Flexibility. Scalability. Modularity. Unraid empowers you to build the system you’ve always wanted using your preferred hardware, software, and operating systems.
unRAID Server - A scalable, consumer-oriented, server operating system.