Deciding between RAIDZ-1 and RAIDZ-2 (Configuring ZFS)

Episode Overview

• The episode addresses a common question for home lab users: how to configure disks using OpenZFS.
• It focuses on a typical scenario involving a moderate number of disks (between 4 and 12).
• The discussion breaks down the primary decision between using RAIDZ-1 and RAIDZ-2 configurations.
• The core difference is explained in terms of fault tolerance and the level of data redundancy each option provides.

Key Concepts

• Home Lab Configuration: For a typical home setup with 4-12 disks, the recommended approach is to create a single RAIDZ virtual device (VDEV) that includes all the disks.
• RAIDZ-1 (Single Parity): This configuration provides single-disk redundancy. It can tolerate the failure of any one disk in the array without data loss. However, if a second disk fails before the first is replaced and the array is rebuilt (resilvered), all data will be lost.
• RAIDZ-2 (Double Parity): This configuration offers a higher level of data protection by using double parity. It can tolerate the failure of any two disks simultaneously without data loss, giving the user a much safer window to perform replacements.
• Redundancy Trade-off: The choice between RAIDZ-1 and RAIDZ-2 is fundamentally a decision about how much redundancy and data safety you require, with RAIDZ-2 offering more security at the cost of less usable storage space.

Quotes

• At 00:13 - "probably, you're going to create one RAIDZ group and you're going to put all your discs in it" - Explaining the most common and straightforward configuration for a home lab with a moderate number of drives.
• At 00:41 - "Whether it's RAIDZ-1 or RAIDZ-2, it comes down to how much redundancy do you want" - Highlighting the central factor that should guide the user's decision between the two RAIDZ levels.
• At 01:01 - "With RAIDZ-2, you can lose two discs without doing any replacements and you'll still have your data" - Clearly stating the practical benefit and increased fault tolerance of choosing the RAIDZ-2 configuration.

Takeaways

• For a home lab with 4-12 drives, simplify your setup by creating a single RAIDZ pool containing all available disks rather than multiple smaller VDEVs.
• Use RAIDZ-1 if you are willing to accept the risk of total data loss if a second drive fails during the rebuild process of the first failed drive.
• Opt for RAIDZ-2 for significantly better data protection, as it allows two drives to fail simultaneously, which is a safer choice for critical data, especially with larger capacity drives where rebuild times are longer.