我发出 dd 命令清空硬盘。命令成功完成，但只有部分硬盘被覆盖：
mint@mint ~ $ sudo dd if=/dev/zero of=/dev/sda
dd: writing to ‘/dev/sda’: Input/output error
258416001+0 records in
258416000+0 records out
132308992000 bytes (132 GB) copied, 3741.09 s, 35.4 MB/s
下图显示了硬盘的配置：
mint@mint ~ $ sudo fdisk -l /dev/sda
Disk /dev/sda: 320.1 GB, 320072933376 bytes
255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x8f45867a
Device Boot Start End Blocks Id System
笔记：
- 我发出 dd 命令后重建了分区表。这就是分区表显示出来的原因。
- 硬盘有坏扇区，其中 200 个处于待处理状态。我发出了 dd 命令来强制重新分配这些坏扇区。
- 写入速度似乎不错，为 34MB/s，因此我想将 Linux 安装在磁盘磨损部分以外的分区上。我不担心数据丢失，因为我不打算在硬盘上存储任何有价值的数据。
- 尽管存在坏扇区，dd 命令也没有导致任何 I/O 错误。
smartctl输出：
mint@mint ~ $ sudo smartctl -a /dev/sda
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.13.0-37-generic] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Scorpio Black
Device Model: WDC WD3200BEKT-75PVMT0
Serial Number: WD-WXC1A2127646
LU WWN Device Id: 5 0014ee 6abb45855
Firmware Version: 01.01A01
User Capacity: 320,072,933,376 bytes [320 GB]
Sector Size: 512 bytes logical/physical
Rotation Rate: 7200 rpm
Device is: In smartctl database [for details use: -P show]
ATA Version is: ATA8-ACS (minor revision not indicated)
SATA Version is: SATA 2.6, 3.0 Gb/s
Local Time is: Sat Jun 13 05:27:23 2015 UTC
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: FAILED!
Drive failure expected in less than 24 hours. SAVE ALL DATA.
See vendor-specific Attribute list for failed Attributes.
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: ( 5760) 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: ( 60) minutes.
Conveyance self-test routine
recommended polling time: ( 5) minutes.
SCT capabilities: (0x7035) 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 200 200 051 Pre-fail Always - 0
3 Spin_Up_Time 0x0027 163 160 021 Pre-fail Always - 816
4 Start_Stop_Count 0x0032 099 099 000 Old_age Always - 1156
5 Reallocated_Sector_Ct 0x0033 133 133 140 Pre-fail Always FAILING_NOW 561
7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0
9 Power_On_Hours 0x0032 073 073 000 Old_age Always - 19736
10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0
11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0
12 Power_Cycle_Count 0x0032 099 099 000 Old_age Always - 1151
191 G-Sense_Error_Rate 0x0032 001 001 000 Old_age Always - 2733
192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 64
193 Load_Cycle_Count 0x0032 137 137 000 Old_age Always - 191394
194 Temperature_Celsius 0x0022 105 090 000 Old_age Always - 38
196 Reallocated_Event_Count 0x0032 194 194 000 Old_age Always - 6
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 0
198 Offline_Uncorrectable 0x0030 100 253 000 Old_age Offline - 0
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0008 100 253 000 Old_age Offline - 0
240 Head_Flying_Hours 0x0032 074 074 000 Old_age Always - 19078
241 Total_LBAs_Written 0x0032 200 200 000 Old_age Always - 37643305479
242 Total_LBAs_Read 0x0032 200 200 000 Old_age Always - 31320890404
254 Free_Fall_Sensor 0x0032 197 197 000 Old_age Always - 3
SMART Error Log Version: 1
ATA Error Count: 48 (device log contains only the most recent five errors)
CR = Command Register [HEX]
FR = Features Register [HEX]
SC = Sector Count Register [HEX]
SN = Sector Number Register [HEX]
CL = Cylinder Low Register [HEX]
CH = Cylinder High Register [HEX]
DH = Device/Head Register [HEX]
DC = Device Command Register [HEX]
ER = Error register [HEX]
ST = Status register [HEX]
Powered_Up_Time is measured from power on, and printed as
DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes,
SS=sec, and sss=millisec. It "wraps" after 49.710 days.
Error 48 occurred at disk power-on lifetime: 19723 hours (821 days + 19 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
01 51 08 81 1d 67 ef Error: AMNF 8 sectors at LBA = 0x0f671d81 = 258416001
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 08 80 1d 67 ef 00 00:36:32.852 READ DMA
ef 10 02 00 00 00 a0 00 00:36:32.852 SET FEATURES [Enable SATA feature]
ec 00 00 00 00 00 a0 00 00:36:32.850 IDENTIFY DEVICE
ef 03 46 00 00 00 a0 00 00:36:32.850 SET FEATURES [Set transfer mode]
Error 47 occurred at disk power-on lifetime: 19723 hours (821 days + 19 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
40 51 08 81 1d 67 ef Error: UNC 8 sectors at LBA = 0x0f671d81 = 258416001
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 08 80 1d 67 ef 00 00:36:31.120 READ DMA
ef 10 02 00 00 00 a0 00 00:36:31.119 SET FEATURES [Enable SATA feature]
ec 00 00 00 00 00 a0 00 00:36:31.118 IDENTIFY DEVICE
ef 03 46 00 00 00 a0 00 00:36:31.118 SET FEATURES [Set transfer mode]
Error 46 occurred at disk power-on lifetime: 19723 hours (821 days + 19 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
40 51 08 81 1d 67 ef Error: UNC 8 sectors at LBA = 0x0f671d81 = 258416001
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 08 80 1d 67 ef 00 00:36:29.389 READ DMA
ef 10 02 00 00 00 a0 00 00:36:29.389 SET FEATURES [Enable SATA feature]
ec 00 00 00 00 00 a0 00 00:36:29.387 IDENTIFY DEVICE
ef 03 46 00 00 00 a0 00 00:36:29.387 SET FEATURES [Set transfer mode]
Error 45 occurred at disk power-on lifetime: 19723 hours (821 days + 19 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
40 51 08 81 1d 67 ef Error: UNC 8 sectors at LBA = 0x0f671d81 = 258416001
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 08 80 1d 67 ef 00 00:36:27.657 READ DMA
ef 10 02 00 00 00 a0 00 00:36:27.657 SET FEATURES [Enable SATA feature]
ec 00 00 00 00 00 a0 00 00:36:27.655 IDENTIFY DEVICE
ef 03 46 00 00 00 a0 00 00:36:27.655 SET FEATURES [Set transfer mode]
Error 44 occurred at disk power-on lifetime: 19723 hours (821 days + 19 hours)
When the command that caused the error occurred, the device was active or idle.
After command completion occurred, registers were:
ER ST SC SN CL CH DH
-- -- -- -- -- -- --
40 51 08 81 1d 67 ef Error: UNC 8 sectors at LBA = 0x0f671d81 = 258416001
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
c8 00 08 80 1d 67 ef 00 00:36:25.926 READ DMA
ef 10 02 00 00 00 a0 00 00:36:25.926 SET FEATURES [Enable SATA feature]
ec 00 00 00 00 00 a0 00 00:36:25.924 IDENTIFY DEVICE
ef 03 46 00 00 00 a0 00 00:36:25.924 SET FEATURES [Set transfer mode]
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% 8 -
# 2 Short offline Completed without error 00% 8 -
# 3 Short offline Completed without error 00% 8 -
# 4 Short offline Completed without error 00% 8 -
# 5 Short offline Completed without error 00% 8 -
# 6 Short offline Completed without error 00% 8 -
# 7 Short offline Completed without error 00% 7 -
# 8 Short offline Completed without error 00% 7 -
# 9 Short offline Completed without error 00% 1 -
#10 Short offline Completed without error 00% 1 -
#11 Short offline Completed without error 00% 1 -
#12 Short offline Completed without error 00% 1 -
#13 Short offline Completed without error 00% 1 -
#14 Short offline Completed without error 00% 1 -
#15 Short offline Completed without error 00% 1 -
#16 Short offline Completed without error 00% 1 -
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
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.
答案1
dd输出明确指出发生了 I/O 错误。可能是底层磁盘无法重新分配备用扇区，或者以不可恢复的方式发生故障（例如：SATA 链接丢失）。
尝试使用 ddrescue，发出以下命令：ddrescue /dev/zero /dev/sda -f -D。它会改变什么吗？
答案2
我已经看到由于写入经过缓存而发生同样的事情。dd默认情况write下，系统调用一次 512 字节。这会经过使用 4096 字节块的缓存层。但底层媒体仍然使用 512 字节扇区。
因此，当系统dd调用时write，内核将从磁盘加载 4096 字节块，以便更改 512 字节并将其写回。当发生这种情况时，读取步骤会失败，因此内核永远不会进入写入步骤。
我解决这个问题的方法是绕过缓存。指定oflag=direct绕过写入操作的缓存层。由于这会导致性能显著下降，因此我仅使用它通过使用seek=(offset) 和来写入单个坏扇区count=1。