CentOS describes itself as "… a stable, predictable, manageable, and reproducible platform derived from the sources of Red Hat Enterprise Linux (RHEL). Rockstor is a specialty Linux distro designed to support Btrfs-based network-attached storage (NAS) devices.
CentOS 7 (1511)
CentOS describes itself as "… a stable, predictable, manageable, and reproducible platform derived from the sources of Red Hat Enterprise Linux (RHEL)." CentOS began as an independent project offering something close to the RHEL experience without the hefty licensing fees. Since then, Red Hat has embraced the project and now acts as an official CentOS sponsor. The latest release, CentOS 7, 1511, is based on RHEL 7.2. Highlights of the new release include enhancements for identity management, containers, and software-defined networking.
Rockstor 3.8
Rockstor is a specialty Linux distro designed to support Btrfs-based network-attached storage (NAS) devices. You can set up your Rockstor NAS device on commodity hardware, or run Rockstor as a virtual machine on a Xen, KVM, or VMware host. The copy-on-write Btrfs
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Set up network-attached storage and manage it from a web interface with Rockstor, the easy-to-install and free Linux distribution that uses the still new Btrfs filesystem.
CentOS describes itself as "… a community-supported distribution derived from sources freely provided to the public by Red Hat for Red Hat Enterprise Linux (RHEL)." Tails is a specialty Live Linux system designed for easy access to the TOR anonymity network.