Use our professional zfs raid calculator to estimate your usable storage capacity, redundancy levels, and efficiency for ZFS pools. Planning a NAS or server array requires precision to balance data safety and cost.
zfs raid calculator
zfs raid calculator Formula:
Usable Capacity ($C_{u}$) = $(N – P) \times S \times (1 – O)$
Source: Oracle ZFS Documentation & TrueNAS Docs
Variables:
- N: Total Number of Drives in the vdev.
- S: Individual Drive Size (Manufacturer capacity).
- P: Parity Drives (1 for RAIDZ1, 2 for RAIDZ2, 3 for RAIDZ3).
- O: ZFS Overhead (Approx. 1/64 reserve plus metadata).
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What is zfs raid calculator?
A ZFS RAID calculator is a specialized tool used by system administrators and NAS enthusiasts to determine the actual storage space available after configuring a ZFS pool. Unlike traditional RAID, ZFS (Zettabyte File System) manages its own RAID levels (RAIDZ) which integrate data integrity features.
Calculating the usable space correctly is vital because ZFS performs best when usage stays below 80%. This calculator helps you plan your storage budget while ensuring you have enough parity for data safety.
How to Calculate zfs raid calculator (Example):
- Identify your drive count (e.g., 6 drives).
- Identify drive size (e.g., 10 TB each).
- Choose RAIDZ2 (2 drives for parity).
- Subtract parity from total: $6 – 2 = 4$ usable drives.
- Multiply by size: $4 \times 10 = 40$ TB.
- Factor in overhead (approx. 2-3%): $40 \times 0.98 = 39.2$ TB.
Frequently Asked Questions (FAQ):
Is RAIDZ2 better than RAIDZ1? RAIDZ2 is safer as it allows two drives to fail simultaneously without data loss, whereas RAIDZ1 only allows one.
Why is usable space less than calculated? ZFS reserves a small portion of space (roughly 1.5% to 3%) for metadata and filesystem management.
What is the maximum drive count for a vdev? While technically unlimited, the best practice is usually 8-12 drives per vdev for performance.
Can I add drives to a RAIDZ vdev later? Currently, adding single drives to an existing RAIDZ vdev is limited; typically, you add new vdevs to the pool.