我有一块三星 840 Pro SSD，它已经为 MySQL 数据库服务器工作了一段时间。我感觉它最近变慢了，所以我用 smartctl 测试了一下：
#smartctl -a /dev/sda
smartctl 6.4 2014-10-07 r4002 [x86_64-linux-3.16.0-4-amd64] (local build)
Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Samsung based SSDs
Device Model: Samsung SSD 840 PRO Series
Serial Number: S1AXNSAF210103T
LU WWN Device Id: 5 002538 5a01db814
Firmware Version: DXM05B0Q
User Capacity: 512,110,190,592 bytes [512 GB]
Sector Size: 512 bytes logical/physical
Rotation Rate: Solid State Device
Device is: In smartctl database [for details use: -P show]
ATA Version is: ACS-2, ATA8-ACS T13/1699-D revision 4c
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Fri Mar 27 00:25:00 2020 EDT
SMART support is: Available - device has SMART capability.
SMART support is: Enabled
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED
General SMART Values:
Offline data collection status: (0x00) Offline data collection activity
was never started.
Auto Offline Data Collection: Disabled.
Self-test execution status: ( 0) The previous self-test routine completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: (53956) seconds.
Offline data collection
capabilities: (0x53) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
No Offline surface scan supported.
Self-test supported.
No Conveyance Self-test supported.
Selective Self-test supported.
SMART capabilities: (0x0003) Saves SMART data before entering
power-saving mode.
Supports SMART auto save timer.
Error logging capability: (0x01) Error logging supported.
General Purpose Logging supported.
Short self-test routine
recommended polling time: ( 2) minutes.
Extended self-test routine
recommended polling time: ( 35) minutes.
SCT capabilities: (0x003d) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 1
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
5 Reallocated_Sector_Ct 0x0033 100 100 010 Pre-fail Always - 0
9 Power_On_Hours 0x0032 092 092 000 Old_age Always - 35740
12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always - 18
177 Wear_Leveling_Count 0x0013 085 085 000 Pre-fail Always - 522
179 Used_Rsvd_Blk_Cnt_Tot 0x0013 100 100 010 Pre-fail Always - 0
181 Program_Fail_Cnt_Total 0x0032 100 100 010 Old_age Always - 0
182 Erase_Fail_Count_Total 0x0032 100 100 010 Old_age Always - 0
183 Runtime_Bad_Block 0x0013 100 100 010 Pre-fail Always - 0
187 Uncorrectable_Error_Cnt 0x0032 100 100 000 Old_age Always - 0
190 Airflow_Temperature_Cel 0x0032 073 057 000 Old_age Always - 27
195 ECC_Error_Rate 0x001a 200 200 000 Old_age Always - 0
199 CRC_Error_Count 0x003e 100 100 000 Old_age Always - 0
235 POR_Recovery_Count 0x0012 099 099 000 Old_age Always - 12
241 Total_LBAs_Written 0x0032 099 099 000 Old_age Always - 25524754306
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short offline Completed without error 00% 35740 -
SMART Selective self-test log data structure revision number 1
SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS
1 0 0 Not_testing
2 0 0 Not_testing
3 0 0 Not_testing
4 0 0 Not_testing
5 0 0 Not_testing
255 0 65535 Read_scanning was never started
Selective self-test flags (0x0):
After scanning selected spans, do NOT read-scan remainder of disk.
If Selective self-test is pending on power-up, resume after 0 minute delay.
奇怪的是，它Wear_Leveling_Count是522。但我读到它应该从 100 开始，并随着磁盘磨损逐渐接近 0。
所以我想知道如何解释这个数字？ 是否有更可靠的方法来检查磁盘的健康状况？
答案1
每个 SMART 属性都有两个值：生的价值和规范化值（又称当前值）。在 的输出中smartctl -a，标准化值在标题为 的列下报告VALUE，而原始值在标题下报告RAW_VALUE（请参阅手册页）。
对于Wear_Leveling_Count属性 (ID#177)，标准化值以百分比形式估计剩余寿命，在输出中为 085 或 85%。（原始值 522 对用户来说用处不大，因为它是特定于驱动器的数字，给出了程序擦除周期的总数，按每个块平均计算。）
因此您的驱动器预计剩余寿命为 85%。
看此主题更多信息。不幸的是，大量线程无法正确区分和解释这两个字段（规范化和原始），从而造成极大混乱！