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Online RAID calculator

ZAR has been discontinued
After about twenty years, I felt ZAR can no longer be updated to match the modern requirements, and I decided to retire it.

ZAR is replaced by Klennet Recovery, my new general-purpose DIY data recovery software.

If you are looking specifically for recovery of image files (like JPEG, CR2, and NEF), take a look at Klennet Carver, a separate video and photo recovery software.

You can estimate the RAID characteristics using this RAID calculator. Usage instructions are simple: select the desired array layout, then enter RAID member disk capacities into the corresponding form fields. The rest is done automatically.

For more information about RAID and RAID levels, please refer to RAID 101.

Enter your data below
Array layout
Physical disk size (leave some fields blank if you plan for less than five drives) Disk 1 GB
Disk 2 GB
Disk 3 GB
Disk 4 GB
Disk 5 GB
The results are available below
Total array capacity
Fault tolerance - Maximum anticipated number of simultaneous disk failures.
Space required to maintain fault tolerance information.
Slack - space loss due to drive size inequality; unusable in hardware implementations; may be combined into the separate array in software implementations.
Estimated transfer speed (theoretical estimation only applicable for sustained linear operations; very optimistic in most cases; take it with a grain of salt). Speeds are relative to the single member disk speed. Read speed
Write speed


  • Write speed of a RAID 5 depends upon the controller implementation heavily. The estimation of a write speed is thus not provided for a RAID5.
  • Setups involving more than two member disks in a RAID1 (Mirror) array are allowed but rarely used. Additional backup ("shadow") disks provide additional fault tolerance at the cost of storage space overhead.
  • RAID10 survives any single disk failure and a half of double failures (depending on the assignment of the failed drives).
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