Contec PC-SDD64V User Manual page 5

PC-SDD V Series User's Guide
(1)
Average number of writes before failure [No. of accesses =
1.37 x 10 x -ln(1-
Mean time before failure for write access [Hours]=
Ex. 1) If a 9.6-megabyte file is updated once per five minutes on the PC-SDD64V:
Ex. 2) Three-megabyte swapping interval at which a lifespan of 10 years (87,600
hours) can be expected
(2)
Average number of writes before failure [No. of accesses] =
1.37 x 10 x
Note : The above formula is empirical.
Mean time before failure for write access [Hours] =
Ex.) When a file of about 64 megabytes is updated once per five minutes [12 times an
hour] on the PC-SDD64V
5
When part of the drive is rewritten (total size of files to be updated < total SDD
capacity)
8
0.576[MB]+Size of file being written to [MB]
Note: The above formula is empirical.
Average number of writes before failure [No. of accesses] = 22,047,597
Mean time before failure for write access [Hours] = 22,047,597/12 = 1,837,300
(= about 209 years)
Number of times swapping occurs per hour [No. of times/hour] =
60,682,175/87,600 = 692.7
Swapping interval [Seconds/No. of times] = 3600/692.7 = 5.19
A measured swapping interval of 5.19 seconds or more indicates a life
expectancy of at least 10 years.
When the entire drive is rewritten at once (total size of files to be updated = total
SDD capacity)
1
8
1.16
(-ln0.982)
Mean time before failure for write access [Hours] = 4,325,538/12
= 360,461 (= 41 years approx.)
Total SDD capacity
Average number of writes before failure
Number of writes per hour
= 4,325,538(Fixed value)
Number of writes per hour
1
1.16
x 0.018)
4,325,538
PC-SDD V Series