Proxmox ZFS & Hardware RAID Capacity Calculator
Calculate net usable Proxmox VE ZFS capacity, padding loss, slop space, 80% safe ceiling, ARC RAM, and zpool create CLI script.
Input Parameters
Calculation Results
- Total Number of Disks
- 6 Disks
- Capacity per Disk
- 4
- Capacity Unit
- TB
- ZFS VDEV Topology
- raidz2
- Storage Media Type
- ssd
- Disk Media Specification
- Enterprise SSD
- Number of VDEV Stripes
- 1 VDEVs
- Sector Ashift Value
- 12
- ZFS Recordsize
- 128 KiB
- ZFS Pool Name
- rpool-data
- Total Raw Capacity (Decimal)
- 24 TB
- Total Raw Capacity (Binary)
- 21.83 TiB
- Standard RAID Usable (Decimal)
- 16 TB
- Standard RAID Usable (Binary)
- 14.55 TiB
- Parity & Hot Spare Allocation
- 8 TB
- ZFS Sector Padding Overhead
- 0.45 TB
- ZFS Slop Space Reservation (1/32)
- 0.137 TB
- ZFS Net Usable Capacity (Decimal)
- 15.41 TB
- ZFS Net Usable Capacity (Binary)
- 14.02 TiB
- ZFS 80% Safe Capacity Limit (TB)
- 12.33 TB
- ZFS 80% Safe Capacity Limit (TiB)
- 11.21 TiB
- Disk Fault Tolerance
- 2 drive per VDEV bersamaan
- Estimated Read Performance Gain
- 4×
- Estimated Write Performance Gain
- 1×
- Estimated Random Read IOPS
- 32,000 IOPS
- Estimated Random Write IOPS
- 6,800 IOPS
- Minimum ZFS ARC RAM
- 26 GB
- Recommended Production ZFS ARC RAM
- 32 GB
For Proxmox ZFS, always use IT-Mode HBA controllers instead of hardware RAID cards, paired with Pure Sinewave UPS.
# ===================================================================== # InfraCalc.web.id — ZFS Pool untuk Proxmox VE | Topologi: RAIDZ2 | 6 Drive (24 TB Raw) # Kapasitas Bersih ZFS: 15.41 TB (14.02 TiB) | Batas Aman 80%: 12.33 TB (11.21 TiB) # Ganti ID DISK dengan ID asli dari: ls -l /dev/disk/by-id/ (hindari nama /dev/sdX) # ===================================================================== # 1. Buat ZFS Storage Pool di Terminal Proxmox VE zpool create -f -o ashift=12 -O compression=zstd -O acltype=posixacl -O xattr=sa -O normalization=formD rpool-data \ raidz2 /dev/disk/by-id/nvme-DISK_1 /dev/disk/by-id/nvme-DISK_2 /dev/disk/by-id/nvme-DISK_3 /dev/disk/by-id/nvme-DISK_4 /dev/disk/by-id/nvme-DISK_5 /dev/disk/by-id/nvme-DISK_6 # 2. Rekomendasi Dataset Options untuk Proxmox VM & Container zfs set recordsize=128k rpool-data zfs set atime=off rpool-data # 3. Verifikasi Status Pool zpool status rpool-data zfs list rpool-data
Visual 2D 19" Server Rack & Patch Panel Builder
- 1U–4U (Bottom): Heavy UPS & VRLA Battery Banks mounted at the bottom to lower center of gravity.
- Middle: Compute servers, ZFS storage arrays, and NVRs placed in the center cold-aisle zone.
- Top: Top-of-Rack PoE switches, Cat6 patch panels, and brush organizers for overhead cable trays.
Generate Project BoQ / Cost Estimate (RAB)
| Kode | Material & Equipment | Qty (+15%) | Unit | Unit Price (IDR) | Line Total (IDR) |
|---|---|---|---|---|---|
| UPS-UNIT | Online Pure Sinewave Rackmount UPS (2200 VA) Pure Sinewave, PF 0.8–0.9, AVR | 1 | Unit | Rp 6.800.000 | |
| BATT-VRLA | 12V VRLA Deep-Cycle Battery Bank (~100 Ah Total) Maintenance-Free VRLA Battery | 2 | Unit | Rp 3.700.000 | |
| SRV-DISK | Enterprise NAS / Server Storage Drive & Railkit CMR 7200 RPM 24/7 Enterprise Grade | 4 | Unit | Rp 11.800.000 | |
| RACK-PDU | 19" Server Rack Cabinet + Metered PDU + C13/C14 Cords Includes grounding bar & roof fan unit | 2(Base: 1) | Paket | Rp 9.700.000 | |
| Equipment & Material Subtotal: | Rp 32.000.000 | ||||
| Estimated Installation & Commissioning (10%): | Rp 3.200.000 | ||||
| PPN (11%): | Rp 3.872.000 | ||||
| ESTIMATED GRAND TOTAL: | Rp 39.072.000 | ||||
Note: Unit prices above are initial reference estimates and can be edited inline.Referensi Teknis & BoQ — Built for Network & System Engineers
Technical Accuracy Note: Calculation results are engineering estimates based on standard RFC/IEEE/ITU-T models. Actual field performance may vary due to protocol overhead, hardware specifications, and environmental factors.
How to Use This Tool
- Select your drive count, individual disk capacity (TB or GB), and target ZFS topology (Mirror / RAID 10, RAIDZ1, RAIDZ2, or RAIDZ3).
- Specify the pool ashift (ashift 12 for modern 4K disks), dataset recordsize (128 KiB standard, 16 KiB database, or 1024 KiB backup), and storage media type (NVMe, SSD, or HDD).
- Inspect the net usable ZFS capacity, the 80% performance threshold, estimated IOPS, and ARC RAM requirements, then copy the zpool create command into your Proxmox VE shell.
Worked Example: Proxmox Standard 6 × 4 TB RAIDZ2
Computed example: An array of 6 drives × 4 TB (24 TB / 21.83 TiB raw) in RAIDZ2 yields a net ZFS usable capacity of 15.41 TB (14.02 TiB) after parity, padding loss (0.45 TB), and slop space (0.1374 TB). The 80% safe capacity ceiling is 12.33 TB (11.21 TiB) with a minimum ARC RAM requirement of 26 GB (host recommendation 32 GB).
- Total Physical Drives
- 6 Disks
- Capacity per Drive
- 4
- Capacity Unit
- TB (Decimal Terabyte 10^12)
- ZFS Redundancy Topology
- RAIDZ2 (Dual Parity — Production Recommended)
- Pool ashift (Sector Alignment)
- ashift 12 (4 KiB — Modern NVMe/SSD/HDD standard)
- Dataset recordsize
- 128 KiB (Default ZFS & Proxmox General)
- Storage Media Type
- Enterprise SATA/SAS SSD (~8,000 IOPS)
- Proxmox ZFS Pool Name
- rpool-data
- Total Number of Disks
- 6 Disks
- Capacity per Disk
- 4
- Capacity Unit
- TB
- ZFS VDEV Topology
- raidz2
- Storage Media Type
- ssd
- Disk Media Specification
- Enterprise SSD
- Number of VDEV Stripes
- 1 VDEVs
- Sector Ashift Value
- 12
- ZFS Recordsize
- 128 KiB
- ZFS Pool Name
- rpool-data
- Total Raw Capacity (Decimal)
- 24 TB
- Total Raw Capacity (Binary)
- 21.83 TiB
- Standard RAID Usable (Decimal)
- 16 TB
- Standard RAID Usable (Binary)
- 14.55 TiB
- Parity & Hot Spare Allocation
- 8 TB
- ZFS Sector Padding Overhead
- 0.45 TB
- ZFS Slop Space Reservation (1/32)
- 0.137 TB
- ZFS Net Usable Capacity (Decimal)
- 15.41 TB
- ZFS Net Usable Capacity (Binary)
- 14.02 TiB
- ZFS 80% Safe Capacity Limit (TB)
- 12.33 TB
- ZFS 80% Safe Capacity Limit (TiB)
- 11.21 TiB
- Disk Fault Tolerance
- 2 drive per VDEV bersamaan
- Estimated Read Performance Gain
- 4×
- Estimated Write Performance Gain
- 1×
- Estimated Random Read IOPS
- 32,000 IOPS
- Estimated Random Write IOPS
- 6,800 IOPS
- Minimum ZFS ARC RAM
- 26 GB
- Recommended Production ZFS ARC RAM
- 32 GB
- Terminal Configuration Script (CLI)
- # ===================================================================== # InfraCalc.web.id — ZFS Pool untuk Proxmox VE | Topologi: RAIDZ2 | 6 Drive (24 TB Raw) # Kapasitas Bersih ZFS: 15.41 TB (14.02 TiB) | Batas Aman 80%: 12.33 TB (11.21 TiB) # Ganti ID DISK dengan ID asli dari: ls -l /dev/disk/by-id/ (hindari nama /dev/sdX) # ===================================================================== # 1. Buat ZFS Storage Pool di Terminal Proxmox VE zpool create -f -o ashift=12 -O compression=zstd -O acltype=posixacl -O xattr=sa -O normalization=formD rpool-data \ raidz2 /dev/disk/by-id/nvme-DISK_1 /dev/disk/by-id/nvme-DISK_2 /dev/disk/by-id/nvme-DISK_3 /dev/disk/by-id/nvme-DISK_4 /dev/disk/by-id/nvme-DISK_5 /dev/disk/by-id/nvme-DISK_6 # 2. Rekomendasi Dataset Options untuk Proxmox VM & Container zfs set recordsize=128k rpool-data zfs set atime=off rpool-data # 3. Verifikasi Status Pool zpool status rpool-data zfs list rpool-data
Core Concept & Engineering Notes
How It Was Calculated (Formulas & Steps)
Mathematical Formulas
- Gross Raw Capacity (TB) = Drive Count × Capacity per Drive
- Binary Capacity (TiB) = Decimal TB × 0.9094947 (10^12 to 2^40)
- Standard Usable = Effective Data Drives × Capacity per Drive
- Padding Loss = Standard Usable × Padding Ratio (0.028 for 128k recordsize)
- Slop Space = min((Standard Usable − Padding Loss) × 1/32, 0.1374 TB / 128 GiB)
- Net ZFS Usable = Standard Usable − Padding Loss − Slop Space
- 80% Safe Capacity = Net ZFS Usable × 0.80 (prevents Copy-on-Write performance collapse)
- ARC RAM Recommendation = Base 2 GB + 1 GB per 1 TB Raw Capacity
Step-by-Step Calculation
- Raw Pool Capacity: 6 × 4 TB = 24 TB (21.83 TiB)
- Standard Hardware RAID baseline: 4 effective data drives = 16 TB (14.55 TiB)
- OpenZFS Overheads: RAIDZ sector padding loss = 0.45 TB (128k recordsize), slop space allocation = 0.1374 TB (capped at 128 GiB)
- Net ZFS Usable: 15.41 TB (14.02 TiB); Recommended 80% Safe Capacity ceiling = 12.33 TB (11.21 TiB)
- Host Memory Sizing: Base 2 GB + 1 GB/TB raw = 26 GB ARC RAM (Recommend 32 GB total host RAM)
Frequently Asked Questions (FAQ)
Why is the usable ZFS capacity in Proxmox smaller than standard hardware RAID?
Beyond the ~9% difference between decimal TB (10^12) and binary TiB (2^40) reported by the OS, ZFS reserves Slop Space (1/32 of pool size, up to 128 GiB), sector padding alignment margins on RAIDZ, and internal copy-on-write metadata structures.
Why is it strongly advised never to fill a ZFS pool beyond 80% capacity?
Because ZFS is a Copy-on-Write filesystem. When free capacity drops below 20%, the kernel switches from a high-speed first-fit block allocator to an exhaustive best-fit allocator, escalating fragmentation and drastically depressing write performance.
How much RAM does Proxmox VE require for the ZFS ARC cache?
The standard sizing guideline is 2 GB base RAM for the Proxmox OS plus 1 GB of RAM per 1 TB of raw pool capacity. If inline deduplication is enabled, RAM requirements jump dramatically to at least 5 GB per 1 TB of storage to hold the DDT table in memory.
Why should we always use `/dev/disk/by-id/` rather than `/dev/sda` device names in Proxmox?
Linux device letters such as `/dev/sda` or `/dev/sdb` are dynamically assigned during kernel boot and can shuffle upon reboot or controller port re-cabling. Using persistent `/dev/disk/by-id/` paths binds drives to their permanent serial numbers, preventing failed pool imports.
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References & Notes
- OpenZFS Documentation — Storage Pool Administration & Performance
- Proxmox VE Documentation — ZFS on Linux
Note: Results above are mathematical estimates based on standard formulas. Always verify against official vendor documentation and site conditions before production deployment.
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Engineering Sensitivity Analysis, Response Curve & Technical Citation
1. 1. 3-Point Engineering Sensitivity & Tolerance Envelope
Comparative evaluation across theoretical laboratory bounds (0% loss), current nominal operating point, and conservative field safety bounds (±15% thermal/aging derating).
| Evaluated Parameter | Ideal Theoretical Bound | Nominal Operating Point | Conservative Safety Bound (±15%) | Engineering Derating Rule |
|---|---|---|---|---|
| Total Number of Disks | 5.4 | 6 | 6.9 | Engineering Safety Margin (+15% Overhead) |
| Capacity per Disk | 3.6 | 4 | 4.6 | Engineering Safety Margin (+15% Overhead) |
| Number of VDEV Stripes | 0.9 | 1 | 1.15 | Engineering Safety Margin (+15% Overhead) |
| Sector Ashift Value | 10.8 | 12 | 13.8 | Engineering Safety Margin (+15% Overhead) |
| ZFS Recordsize | 115 | 128 | 147 | Engineering Safety Margin (+15% Overhead) |
2. 2. Mathematical Function Curve & Operating Coordinate (x₀, y₀)
3. 3. Physical Constants & Normative Standard Clauses
Decimal Terabyte (SI) to Binary Tebibyte (IEC) Conversion Ratio
Clause 4 — Binary Prefixes — 1 TB = 10¹² Bytes; 1 TiB = 2⁴⁰ Bytes = 1,099,511,627,776 Bytes.
Temperature Coefficient of Resistance for Copper
International Annealed Copper Standard — Used in thermal derating equation: R(T) = R_20 × [1 + 0.00393 × (T - 20)].
4. 4. Independent Technical & Academic Citation (IEEE / APA 7th / BibTeX / LaTeX)
Use the standard citation formats below to reference this computational methodology in engineering specifications, audit reports, or academic papers.
[IEEE] KalkuNet Engineering Team, "Proxmox ZFS & Hardware RAID Capacity Calculator — Standard Engineering Computational Instrument," KalkuNet Technical Suite, 2026. [Online]. Available: https://kalkunet.com/en/tools/zfs-raid-calculator. [Accessed: 2026-11-08].
[APA 7th] KalkuNet Engineering Team. (2026). Proxmox ZFS & Hardware RAID Capacity Calculator (Production release 2026-11-08) [Engineering computational software]. KalkuNet. https://kalkunet.com/en/tools/zfs-raid-calculator
@software{kalkunet_zfs_raid_calculator_2026,
author = {{KalkuNet Engineering Team}},
title = {{Proxmox ZFS & Hardware RAID Capacity Calculator --- KalkuNet Engineering Suite}},
year = {2026},
publisher = {KalkuNet.com},
url = {https://kalkunet.com/en/tools/zfs-raid-calculator},
urldate = {2026-11-08}
}
% LaTeX Engineering Derivation — Generated via https://kalkunet.com/en/tools/zfs-raid-calculator
\begin{equation}
\text{Model: } Gross Raw Capacity (TB) = Drive Count × Capacity per Drive
\end{equation}
% Parameter Input Terukur: drives = 6, \; driveSize = 4, \; unit = TB, \; topology = raidz2
% Hasil Evaluasi Numerik : totalDrives = \mathbf{6}, \; driveSize = \mathbf{4}, \; unit = \mathbf{TB}