Acronis Drive Monitor - User Guide - Manual (Page 12)

Disk health (%) = Π (100% - (min(limit, attribute_value*Weight)))
where:
100% - an initial health of a disk;
Π - the product of minimums from (limit, attribute_value*Weight) - calculated for each critical
S.M.A.R.T. parameter;
Weight - a weight of each critical S.M.A.R.T. parameter (see a Table 1 below);
limit - a limit of each critical S.M.A.R.T. parameter (see a Table 1 below);
attribute_value - a current parameter's value.
Example:
1. Soft Read Error Rate = 30 (attribute value), weight = 1, limit = 20;
2. Spin Retry Count = 12(attribute value) , weight = 2, limit = 50.
So in this case the disk's health is calculated as the following:
Disk health =(100% – (min(30*1, 20))) * (100-min(12*2, 50))) = 80%*76%=60.8% ≈61%
The following table contains the health related (critical) S.M.A.R.T. attributes affecting the health
value with their weights and maximum limits.
Table 1.
Attribute ID S.M.A.R.T. attribute Weight Limit %
05 Reallocated Sectors Count 2 70
10 Spin Retry Count 2 50
184 End-to-End Error 1 50
196 Reallocation Event Count 1 40
197 Current Pending Sectors Count 1 40
198 Off-Line Uncorrectable Sectors Count 2 70
201 Soft Read Error Rate 1 20
Not critical parameters:
Other S.M.A.R.T. parameters, which have a predefined by manufacturer Threshold value, also affect
a disk's health: after decreasing below the threshold, this parameter subtracts 10% from the current
disk health. This means, when the current health is 90%, 9% will be subtracted.
A Table 2 shows non-critical S.M.A.R.T. parameters, that affect a disk health.
Table 2.