Installation Options: Storage

rXg File System

The rXg platform uses the ZFS (Zettabyte File System) file system, which is a high-performance, scalable file system and volume manager designed by Sun Microsystems. ZFS provides advanced features like data integrity verification, snapshots, copy-on-write, and automatic repair. ZFS eliminates the need for a separate volume manager by managing storage pools dynamically, allowing for easy expansion and redundancy without the need for hardware/software based RAID solutions. ZFS supports high storage capacities, compression, and deduplication, making it ideal for enterprise and cloud environments. With built-in RAID (RAID-Z), self-healing properties, and efficient data management, ZFS is a robust choice for ensuring data reliability and reducing administrative overhead while maintaining optimal performance.

Hardware RAID with ZFS

There are numerous benefits to implementing ZFS in a configuration where the ZFS software has direct access to the drives. ZFS delivers greater efficiency and reliability than hardware RAID in all cases that RG Nets has encountered over the past decade. Running ZFS on top of hardware RAID systems has been demonstrated to result in degraded performance in several instances, even if the hardware RAID system is presenting as JBOD.

• ZFS needs direct disk access (HBA Mode). Hardware RAID hides individual disks from ZFS, preventing these features from working correctly. ZFS is designed to manage disks directly so it can perform the following:

  • Detect and correct silent data corruption
  • Maintain checksums
  • Use self-healing and scrubbing features

• Both ZFS and hardware RAID offer redundancyusing both can lead to:

  • Confusing failure detection
  • Slower performance
  • Difficult recovery

• ZFS rebuilds (resilvering) are faster and safer because they only copy used data, unlike hardware RAID which rebuilds entire disks, increasing risk of failure during the rebuild.

What to do when you have to use a Hardware RAID Controller to attach drives?

• Set RAID Controller to HBA/JBOD/IT mode: if your RAID Controller supports it, configure it to "pass-through" or "IT mode" so ZFS sees each physical disk directly.

• No redundancy in Hardware RAID controller: if HBA mode isn't available, and you must use hardware RAID, only use RAID 0 (no redundancy) on each disk and let ZFS manage redundancy itself. This is a last resort to try to minimize the interference of the RAID Controller with the drives and conflicts with ZFS.

Storage Options during installation

When installing an operating system with ZFS support, choosing the right RAID configuration depends on factors like data redundancy, performance, and storage efficiency. Below are key recommendations for the number of drives and the pros and cons of each and every combination in terms of rXg installation.

Single Disk (No RAID)

• Use Case: Non-critical personal systems or testing environments.
• Pros: Simplicity.
• Cons: No redundancy; data loss if the disk fails.

RAID-Z (RAID-Z1, RAID-Z2, RAID-Z3)

• RAID-Z1 (Single Parity, Like RAID 5)

  • Use Case: Minimum 3 disks; offers redundancy but can only tolerate one disk failure.
  • Pros: Good balance of redundancy and storage capacity.
  • Cons: Risk of data loss if two disks fail.

• RAID-Z2 (Double Parity, Like RAID 6)

  • Use Case: Minimum 4 disks; can withstand two disk failures.
  • Pros: Better reliability than RAID-Z1.
  • Cons: Slightly reduced storage efficiency.

• RAID-Z3 (Triple Parity)

  • Use Case: Minimum 5+ disks; tolerates three disk failures.
  • Pros: Maximum fault tolerance.
  • Cons: More storage overhead.

Mirrored vdevs (Like RAID 1)

• Use Case: Minimum 2 disks per mirror; commonly used in high-performance environments.
• Pros: Fastest rebuild times, best read performance.
• Cons: Requires more disks; less storage efficiency.

Striped vdevs (RAID 0 Not Recommended)

• Use Case: High-performance scenarios with no redundancy.
• Pros: Maximum speed and storage utilization.
• Cons: No fault tolerance; one disk failure means total data loss.

Drive Selection Options

The drive count translates then into specific selection options during the installation process, as shown below for drive count 1-6. Higher drive counts will default to RAID-Z3 configuration style.

Drive count	Installer options
1	Automatic drive selection, no options to consider
2
3
4
5
6