Hey there, let's tackle your slow Seagate ST4000DM004 drive problem step by step. I'll go over your questions and break down the clues from your SMART data below.

一、为什么写入速度突然变慢？ #

Looking at your SMART report, there are a few key red flags that could explain the slowdown:

• 超高的寻道错误率（ID7 Seek_Error_Rate）: The raw value here is 56965298473680 — that's an extremely high number. Even though the normalized value (50) hasn't hit the threshold yet, this means your drive is having a ton of trouble positioning the read/write heads correctly. This directly kills random read/write speeds, and will drag down sequential performance too as the drive wastes time retrying seeks.
• 曾经出现过过热（ID190 Airflow_Temperature_Cel）: The status shows In_the_past, meaning your drive overheated at some point (max temp hit 41°C, which is right at the threshold of 40°C). Overheating can warp the drive platters or damage the head mechanism, leading to long-term performance degradation.
• 硬盘老化: Your drive has 38825 power-on hours — that's roughly 4.4 years of constant use. Mechanical parts like the spindle motor and head actuators wear out over time, which naturally slows down the drive's ability to read/write data efficiently.
• 其他可能性：如果你的盘里文件碎片过多，或者系统后台有磁盘密集型任务（比如备份、索引），也可能导致临时变慢，但结合SMART数据，硬件层面的问题是更核心的原因。

二、硬盘状态有多糟？需要更换吗？ #

Let's be clear: your drive isn't dead yet, but it's definitely showing signs of wear that could get worse quickly:

• 好消息：目前没有坏扇区相关的警报——Reallocated_Sector_Ct（ID5）、Current_Pending_Sector（ID197）、Offline_Uncorrectable（ID198） all show 0, so no data is currently being marked as unreadable.
• 坏消息：The Seek_Error_Rate is a Pre-fail attribute — this means it's a metric that predicts imminent drive failure. Even though it hasn't tripped the threshold yet, the raw value is way too high to ignore. This is a warning sign that the drive's internal mechanics are failing.
• 加上硬盘已经进入生命周期的后期，我强烈建议你：
  1. 立刻备份所有重要数据 — don't wait for a full failure, because these kinds of mechanical issues can escalate suddenly.
  2. 开始准备更换硬盘 — if this drive is used for critical data or daily use, it's only a matter of time before it fails completely. For a 4TB drive, current replacements are reasonably priced, so it's worth the peace of mind.

你的GNOME Disks SMART测试结果： #

=== START OF INFORMATION SECTION ===

Model Family:     Seagate Barracuda 3.5

Device Model:     ST4000DM004-2CV104

Firmware Version: 0001

User Capacity:    4,000,787,030,016 bytes [4.00 TB]

Sector Sizes:     512 bytes logical, 4096 bytes physical

Rotation Rate:    5425 rpm

Device is:        In smartctl database [for details use: -P show]

ATA Version is:   ACS-3 T13/2161-D revision 5

SATA Version is:  SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s)

Local Time is:    Mon Oct 30 10:54:11 2023 HKT

SMART support is: Available - device has SMART capability.

SMART support is: Enabled

....

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   082   064   006    Pre-fail  Always       -       151289776

3 Spin_Up_Time            0x0003   096   095   000    Pre-fail  Always       -       0

4 Start_Stop_Count        0x0032   100   100   020    Old_age   Always       -       211

5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail  Always       -       0

7 Seek_Error_Rate         0x000f   050   049   030    Pre-fail  Always       -       56965298473680

9 Power_On_Hours          0x0032   056   056   000    Old_age   Always       -       38825 (58 73 0)

10 Spin_Retry_Count        0x0013   100   100   097    Pre-fail  Always       -       0

12 Power_Cycle_Count       0x0032   100   100   020    Old_age   Always       -       211

183 Runtime_Bad_Block       0x0032   100   100   000    Old_age   Always       -       0

184 End-to-End_Error        0x0032   100   100   099    Old_age   Always       -       0

187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0

188 Command_Timeout         0x0032   100   099   000    Old_age   Always       -       1 1 2

189 High_Fly_Writes         0x003a   100   100   000    Old_age   Always       -       0

190 Airflow_Temperature_Cel 0x0022   063   039   040    Old_age   Always   In_the_past 37 (Min/Max 34/41 #46)

191 G-Sense_Error_Rate      0x0032   100   100   000    Old_age   Always       -       0

192 Power-Off_Retract_Count 0x0032   100   100   000    Old_age   Always       -       1237

193 Load_Cycle_Count        0x0032   098   098   000    Old_age   Always       -       4930

194 Temperature_Celsius     0x0022   037   061   000    Old_age   Always       -       37 (0 5 0 0 0)

195 Hardware_ECC_Recovered  0x001a   082   064   000    Old_age   Always       -       151289776

197 Current_Pending_Sector  0x0012   100   100   000    Old_age   Always       -       0

198 Offline_Uncorrectable   0x0010   100   100   000    Old_age   Offline      -       0

199 UDMA_CRC_Error_Count    0x003e   200   200   000    Old_age   Always       -       0

240 Head_Flying_Hours       0x0000   100   253   000    Old_age   Offline      -       29774h+18m+41.265s

241 Total_LBAs_Written      0x0000   100   253   000    Old_age   Offline      -       171742318154

242 Total_LBAs_Read         0x0000   100   253   000    Old_age   Offline      -       149227121472

备注：内容来源于stack exchange，提问作者Rimits