smartctl -A をすると、以下のような結果になる（一部）。
TYPE に Pre-fail というのがあるが、これは何だろうか？

=== START OF READ SMART DATA SECTION ===
SMART Attributes Data Structure revision number: 10
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x000f 080 064 044 Pre-fail Always - 108064505
3 Spin_Up_Time 0x0003 099 099 000 Pre-fail Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 18
5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail Always - 1
7 Seek_Error_Rate 0x000f 075 060 030 Pre-fail Always - 30548070