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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)  36000
Number of RAID Groups 10
Number of drives per RAID Group 8
Total Number of Drives: 80
Drive Capacity (GB) 600
RAID Type: R6
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)
428571428571428 hours
48923679060.6653 years
Probability of read error
during rebuild
0.0002879585319810
System MTTDLLSE
(due to read error during rebuild)
7441547670476.85 hours
849491743.205119 years
Combined system MTTDLTOTAL 7314540827218.92 hours
834993245.116315 years
Probability of data loss over time
1 year 0.0000000011976145
5 years 0.0000000059880724
10 years 0.0000000119761447