我有一台家庭实验室级服务器，几个月前我将 4 个 Crucial MX500 磁盘放入其中。其中一张磁盘（它们都很相似）具有以下 SMART 详细信息：
smartctl 6.5 2016-05-07 r4318 [x86_64-linux-3.10.0-957.12.2.el7.x86_64] (local build)
Copyright (C) 2002-16, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Crucial/Micron BX/MX1/2/3/500, M5/600, 1100 SSDs
Device Model: CT500MX500SSD1
Serial Number: XXXXXXXXXXX
LU WWN Device Id: 5 00a075 1e1e22806
Firmware Version: M3CR023
User Capacity: 500,107,862,016 bytes [500 GB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: Solid State Device
Form Factor: 2.5 inches
Device is: In smartctl database [for details use: -P show]
ATA Version is: ACS-3 T13/2161-D revision 5
SATA Version is: SATA >3.2 (0x1ff), 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Fri Aug 9 17:29:43 2019 CST
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: (0x80) Offline data collection activity
was never started.
Auto Offline Data Collection: Enabled.
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: ( 0) seconds.
Offline data collection
capabilities: (0x7b) SMART execute Offline immediate.
Auto Offline data collection on/off support.
Suspend Offline collection upon new
command.
Offline surface scan supported.
Self-test supported.
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: ( 30) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x0031) SCT Status supported.
SCT Feature Control supported.
SCT Data Table supported.
SMART Attributes Data Structure revision number: 16
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
1 Raw_Read_Error_Rate 0x002f 100 100 000 Pre-fail Always - 0
5 Reallocate_NAND_Blk_Cnt 0x0032 100 100 010 Old_age Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 554
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 35
171 Program_Fail_Count 0x0032 100 100 000 Old_age Always - 0
172 Erase_Fail_Count 0x0032 100 100 000 Old_age Always - 0
173 Ave_Block-Erase_Count 0x0032 092 092 000 Old_age Always - 127
174 Unexpect_Power_Loss_Ct 0x0032 100 100 000 Old_age Always - 9
180 Unused_Reserve_NAND_Blk 0x0033 000 000 000 Pre-fail Always - 43
183 SATA_Interfac_Downshift 0x0032 100 100 000 Old_age Always - 0
184 Error_Correction_Count 0x0032 100 100 000 Old_age Always - 0
187 Reported_Uncorrect 0x0032 100 100 000 Old_age Always - 0
194 Temperature_Celsius 0x0022 064 046 000 Old_age Always - 36 (Min/Max 0/54)
196 Reallocated_Event_Count 0x0032 100 100 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 100 100 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 100 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 100 100 000 Old_age Always - 0
202 Percent_Lifetime_Remain 0x0030 092 092 001 Old_age Offline - 8
206 Write_Error_Rate 0x000e 100 100 000 Old_age Always - 0
210 Success_RAIN_Recov_Cnt 0x0032 100 100 000 Old_age Always - 0
246 Total_Host_Sector_Write 0x0032 100 100 000 Old_age Always - 7227541253
247 Host_Program_Page_Count 0x0032 100 100 000 Old_age Always - 128825080
248 FTL_Program_Page_Count 0x0032 100 100 000 Old_age Always - 1974407892
我试图弄清楚属性202是如何计算的，因为它似乎下降得非常快。我在机器上安装了 ZFS，正常运行时间为 41 天，zpool iostat -v它显示：
capacity operations bandwidth
pool alloc free read write read write
----------------------------------- ----- ----- ----- ----- ----- -----
neo 1.10T 727G 123 174 4.84M 2.27M
raidz1 1.10T 727G 123 174 4.84M 2.27M
ata-CT500MX500SSD1_1XXXXXXXXXXX - - 31 44 1.23M 597K
ata-CT500MX500SSD1_1XXXXXXXXXXX - - 30 42 1.19M 567K
ata-CT500MX500SSD1_1XXXXXXXXXXX - - 31 44 1.23M 597K
ata-CT500MX500SSD1_1XXXXXXXXXXX - - 30 42 1.19M 567K
----------------------------------- ----- ----- ----- ----- ----- -----
据我了解，每个正在写入的磁盘不到 1MB/s。粗略估计我写入的数据量为每天 1MB/s = 86GB 或每月 2.5TB。每月额定 180TBW / 2.5TB 大约是 72 个月或 6 年。但是，我在大约 2.5 个月的时间里就减少了 8%。
我想知道属性202是如何计算的，所以我可以手工计算并开始尝试弄清楚我是否有某种类型的写入放大问题。我有点犹豫要不要相信 SMART 统计数据，因为它们显示了 23 天的 PoH，即使系统有 41 天的正常运行时间，而且特定型号的磁盘也有一个臭名昭著的CurrentPendingSector问题。