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RAID Reliability Calculator

This RAID calculator computes storage system reliability using well-known MTTDL methodology.
Supported RAID levels are RAID 1, RAID 5, RAID 10 (1+0), and RAID 6.

Mission time (year): 
RAID Type:
Number of drives in a RAID group:
Equals 2 for RAID1. Usually in the range between 3 and 12 for other RAIDs. Must be an even number for RAID10.
Number of RAID groups:
Drive Capacity (GB):
Drive Throughput (MB/s):
Usually in the range between 40 MB/s (SATA/7200) and 100 MB/s (SAS/15K).
Drive MTBF (hour): 
or
To use this parameter clear the field below.
Annual failure rate (%):
This value overrides the selection from the Drive MTBF field above.
Clear this field to use the Drive MTBF parameter.
Latent Sector Error (LSE) rate:
Usually in the range between 1.0e-17 and 1.0e-13. The lower value is better.
Time to replace failed drive (hour): 
0 if hot spare is available.
Rebuild rate (%):
or
To use this parameter clear the field below.
Time to rebuild
(hour):
This value overrides the selection from the Rebuild rate field above.
Clear this field to use the Rebuild rate parameter.


Results:

Total Usable Storage Capacity (GB)  42000
Number of RAID Groups 10
Number of drives per RAID Group 8
Total Number of Drives: 80
Drive Capacity (GB) 600
RAID Type: R5
Drive Throughput (MB/s) 100
Drive MTBF (hour) 2000000
Drive Annual Failure Rate (%) 0.438
Drive MTTR (hour) 3.33333333333333
System MTTDLDF
(due to multiple drive failures)
2142857142.85714 hours
244618.395303327 years
Probability of read error
during rebuild
0.0003359435583220
System MTTDLLSE
(due to read error during rebuild)
74417262.6046833 hours
8495.12130190448 years
Combined system MTTDLTOTAL 71919633.5516744 hours
8210.00383009982 years
Probability of data loss over time
1 year 0.0001217952051977
5 years 0.0006088277033346
10 years 0.0012172847354970