Root pool – Create pools with slices by using the s* identifier
Non-root pools – Create non-root pools with whole disks by using the d* identifier.
Mirrored storage pools – Consume more disk space but generally perform better with small random reads
Mirrored storage pools are also more flexible in that you can detach, attach, and replace existing devices in the pool.
RAID-Z storage pools – Can be created with 3 parity strategies, where parity equals 1 (raidz), 2 (raidz2), or 3 (raidz3).
A RAID-Z configuration maximizes disk space and generally performs well when data is written and read in large chunks (128K or more). Create a single-parity RAIDZ (raidz) configuration at 3 disks (2+1).
A RAIDZ-2 configuration offers better data availability, and performs similarly to RAID-Z. RAIDZ-2 has significantly better mean time to data loss (MTTDL) than either RAID-Z or 2-way mirrors. Create a double-parity RAID-Z (raidz2) configuration at 6 disks (4+2).
A RAIDZ-3 configuration maximizes disk space and offers excellent availability because it can withstand 3 disk failures. Create a triple-parity RAID-Z (raidz3) configuration at 8 disks (5+3).