There are several ways to aggregate disks and increase fault tolerance: by hardware RAID (PERC cards, …), by pseudo RAID (Intel MatrixRAID, Promise FastTrak …), by software RAID (Vinum, GEOM, ZFS).

PERC 5/6 (SATA/SAS)

This is hardware RAID controllers manufatured by LSI and installed on DELL servers. Hardware RAID offers good performance and does not solicit system resources but they are expensive and proprietary. Native FreeBSD commands native mfiutil and mptutil advantageously replace the MegaCLI tool provided by LSI, this tool was very poorly documented and required Linux compatibility.

Ataraid

This is the FreeBSD driver for managing the pseudo RAID available on computers fitted for example with Intel MatrixRAID or JMicron. The pseudo RAID solves the problem of starting the operating system from a software RAID, it has the advantage of its low cost but keep the burden of a proprietary design (unable to change the controller without losing the RAID volume) and the pitfalls of software RAID (more or less intensive use of system resources).

GEOM

It is the main storage framework on FreeBSD, it allows chaining module on a producer/consumer model. A wide range of module are availables allowing to have mirror, stripe, raid3 and raid5.

Vinum

Vinum is the historical FreeBSD software RAID based on the Veritas™ Volume Manager. It supports RAID-0, RAID-1 and RAID-5 configuration and has the advantage of being hardware independent.

ZFS

It is the combination of a filesystem and volume manager, so it integrates the functionality of a software RAID, and other more advanced such as deduplication, verification of data integrity, snapshots, … This approach is the one preferred in this document.