1.oops ~ # smartctl -H /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.3.1-gentoo] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: FAILED! <----result後邊的結果：PASSED，這表示硬盤健康狀態良好；如果這裏顯示Failure，那麼最好立刻給服務器更換硬盤
Drive failure expected in less than 24 hours. SAVE ALL DATA.
Failed Attributes:
ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE
5 Reallocated_Sector_Ct 0x0033 001 001 036 Pre-fail Always FAILING_NOW 4095
2.oops ~ # smartctl -C -t short /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.3.1-gentoo] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF OFFLINE IMMEDIATE AND SELF-TEST SECTION ===
Sending command: "Execute SMART Short self-test routine immediately in captive mode".
Drive command "Execute SMART Short self-test routine immediately in captive mode" successful.
Testing has begun.
Please wait 1 minutes for test to complete.
Test will complete after Tue Nov 5 12:19:54 2013
3.oops ~ # smartctl -l selftest /dev/sdb2
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.3.1-gentoo] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short captive Completed: unknown failure 90% 36265 0
# 2 Short captive Completed: unknown failure 90% 36265 0
4.oops ~ # smartctl -l error /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.3.1-gentoo] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF READ SMART DATA SECTION ===
SMART Error Log Version: 1
ATA Error Count: 94 (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 94 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0 Device Fault; Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
a1 00 00 00 00 00 a0 00 00:14:55.632 IDENTIFY PACKET DEVICE
ec 00 00 00 00 00 a0 00 00:14:55.631 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:55.480 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:55.480 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:55.173 [VENDOR SPECIFIC]
Error 93 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
ec 00 00 00 00 00 a0 00 00:14:55.631 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:55.480 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:55.480 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:55.173 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 ff 00:14:55.173 NOP [Abort queued commands]
Error 92 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0 Device Fault; Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
a1 00 00 00 00 00 a0 00 00:14:50.171 IDENTIFY PACKET DEVICE
ec 00 00 00 00 00 a0 00 00:14:50.171 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:50.020 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:50.020 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:49.713 [VENDOR SPECIFIC]
Error 91 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
ec 00 00 00 00 00 a0 00 00:14:50.171 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:50.020 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:50.020 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:49.713 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 ff 00:14:49.713 NOP [Abort queued commands]
Error 90 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0 Device Fault; Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
a1 00 00 00 00 00 a0 00 00:14:49.686 IDENTIFY PACKET DEVICE
ec 00 00 00 00 00 a0 00 00:14:49.661 IDENTIFY DEVICE
2f 00 01 10 00 00 a0 00 00:14:49.632 READ LOG EXT
60 00 00 ff ff ff 4f 00 00:14:46.851 READ FPDMA QUEUED
60 00 00 ff ff ff 4f 00 00:14:46.847 READ FPDMA QUEUED
4.smartctl -a /dev/sdb
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.3.1-gentoo] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Seagate Barracuda 7200.11
Device Model: ST31000333AS
Serial Number: 9TE19F5L
LU WWN Device Id: 5 000c50 010aad5e2
Firmware Version: CC1H
User Capacity: 1,000,204,886,016 bytes [1.00 TB]
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 T13/1699-D revision 4
SATA Version is: SATA 2.6, 3.0 Gb/s
Local Time is: Tue Nov 5 11:48:20 2013 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: 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: (0x82) Offline data collection activity
was completed without error.
Auto Offline Data Collection: Enabled.
Self-test execution status: ( 73) The previous self-test completed having
a test element that failed and the test
element that failed is not known.
Total time to complete Offline
data collection: ( 625) 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: ( 1) minutes.
Extended self-test routine
recommended polling time: ( 208) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x103f) SCT Status supported.
SCT Error Recovery Control supported.
SCT Feature Control supported.
SCT Data Table supported.
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 116 099 006 Pre-fail Always - 114128654
3 Spin_Up_Time 0x0003 100 100 000 Pre-fail Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 85
5 Reallocated_Sector_Ct 0x0033 001 001 036 Pre-fail Always FAILING_NOW 4095 <-------
7 Seek_Error_Rate 0x000f 084 060 030 Pre-fail Always - 281473872
9 Power_On_Hours 0x0032 059 059 000 Old_age Always - 36265
10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 037 020 Old_age Always - 85
184 End-to-End_Error 0x0032 100 100 099 Old_age Always - 0
187 Reported_Uncorrect 0x0032 090 090 000 Old_age Always - 10
188 Command_Timeout 0x0032 100 097 000 Old_age Always - 73015558161
189 High_Fly_Writes 0x003a 001 001 000 Old_age Always - 856
190 Airflow_Temperature_Cel 0x0022 070 054 045 Old_age Always - 30 (Min/Max 23/31)
194 Temperature_Celsius 0x0022 030 046 000 Old_age Always - 30 (0 16 0 0 0)
195 Hardware_ECC_Recovered 0x001a 052 022 000 Old_age Always - 114128654
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 - 269680996540835
241 Total_LBAs_Written 0x0000 100 253 000 Old_age Offline - 481731982
242 Total_LBAs_Read 0x0000 100 253 000 Old_age Offline - 1978196986
SMART Error Log Version: 1
ATA Error Count: 96 (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 96 occurred at disk power-on lifetime: 36265 hours (1511 days + 1 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
-- -- -- -- -- -- --
04 51 00 00 00 00 00 Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
b0 d4 00 81 4f c2 00 00 01:51:33.197 SMART EXECUTE OFF-LINE IMMEDIATE
b0 d0 01 00 4f c2 00 00 01:51:33.112 SMART READ DATA
ec 00 01 00 00 00 00 00 01:51:33.102 IDENTIFY DEVICE
ec 00 01 00 00 00 00 00 01:51:33.100 IDENTIFY DEVICE
b0 d5 01 01 4f c2 00 00 01:49:22.563 SMART READ LOG
Error 95 occurred at disk power-on lifetime: 36265 hours (1511 days + 1 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
-- -- -- -- -- -- --
04 51 00 00 00 00 00 Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
b0 d4 00 81 4f c2 00 00 01:48:43.940 SMART EXECUTE OFF-LINE IMMEDIATE
b0 d0 01 00 4f c2 00 00 01:48:43.876 SMART READ DATA
ec 00 01 00 00 00 00 00 01:48:43.866 IDENTIFY DEVICE
ec 00 01 00 00 00 00 00 01:48:43.865 IDENTIFY DEVICE
b0 d5 01 01 4f c2 00 00 01:45:49.010 SMART READ LOG
Error 94 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0 Device Fault; Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
a1 00 00 00 00 00 a0 00 00:14:55.632 IDENTIFY PACKET DEVICE
ec 00 00 00 00 00 a0 00 00:14:55.631 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:55.480 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:55.480 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:55.173 [VENDOR SPECIFIC]
Error 93 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
ec 00 00 00 00 00 a0 00 00:14:55.631 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:55.480 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:55.480 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:55.173 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 ff 00:14:55.173 NOP [Abort queued commands]
Error 92 occurred at disk power-on lifetime: 36263 hours (1510 days + 23 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
-- -- -- -- -- -- --
04 71 04 9d 00 32 e0 Device Fault; Error: ABRT
Commands leading to the command that caused the error were:
CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name
-- -- -- -- -- -- -- -- ---------------- --------------------
a1 00 00 00 00 00 a0 00 00:14:50.171 IDENTIFY PACKET DEVICE
ec 00 00 00 00 00 a0 00 00:14:50.171 IDENTIFY DEVICE
ff 00 00 00 00 00 00 00 00:14:50.020 [VENDOR SPECIFIC]
00 00 00 00 00 00 00 04 00:14:50.020 NOP [Abort queued commands]
ff 00 00 00 00 00 00 00 00:14:49.713 [VENDOR SPECIFIC]
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Short captive Completed: unknown failure 90% 36265 0
# 2 Short captive Completed: unknown failure 90% 36265 0
# 3 Extended offline Completed: unknown failure 90% 36265 0
# 4 Extended offline Completed: unknown failure 90% 36264 0
# 5 Extended offline Completed: unknown failure 90% 36264 0
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.
#smartctl -A /dev/sda 查看硬盤的詳細信息
#smartctl -s on /dev/sda 如果沒有打開SMART技術，使用該命令打開SMART技術。
#smartctl -t short /dev/sda 後臺檢測硬盤，消耗時間短；
#smartctl -t long /dev/sda 後臺檢測硬盤，消耗時間長；
#smartctl -C -t /dev/sda short前臺檢測硬盤，消耗時間短；
#smartctl -C -t /dev/sda long前臺檢測硬盤，消耗時間長。其實就是利用硬盤SMART的自檢程序。
#smartctl -X /dev/sda 中斷後臺檢測硬盤。
#smartctl -l selftest /dev/sda 顯示硬盤檢測日誌。
#smartctl -l error /dev/sda 顯示硬盤錯誤彙總
壞道修復
檢查: smartctl -l selftest /dev/sda
卸載: umount /dev/sda*
修復: badblocks /dev/sda
badblocks -s -v -c 32 /dev/sdb
Checking blocks 0 to 976762583
Checking for bad blocks (read-only test): 0.20% done, 0:17 elapsed. (0/0/0 errors)
檢測過程是可以中途終止，也可以指定區塊重新開始。
sudo badblock -s -v -c 32 /dev/sd* 976762583 125637824 （注意此處結束區塊在前，起始區塊在後）
修復壞道
如果只是邏輯壞道，你可以
直接fsck
fsck -a /dev/sdb
或者格式化
如果是物理壞道，你需要
a.備份硬盤數據
b.刪除所有硬盤分區 <--可以隔離壞塊
c.根據壞塊位置以及大小，估算出所佔空間。然後重新分區隔離損壞部分。btw：壞道是會擴散的，所以儘可能隔離掉多些空間。
http://www.kbnix.com/2013/07/17/check_and_repari_linux_disk_bad_block
http://www.linuxidc.com/Linux/2012-07/65723.htm
2）有些壞的分區處
#debugreiserfs /dev/sda1 | grep -i 'blocksize'
#badblocks -n -b 4096 -o badblocksfile /dev/sda1 把壞塊區標識出來
#mkfs.reiserfs --badblocks badblocksfile /dev/sda1
#reiserfsck --fix--fixable --badblocks badblocksfile /dev/sda1
badblocks -w是破壞性的檢查
badblocks -b 4096 -c 16 /dev/sda3 -o 1.txt
1.oops ~ # badblocks -s -b 4096 -c 16 /dev/sdb1 -o bad.sdb1
Checking for bad blocks (read-only test): 13.34% done, 2:24 elapsed. (0/0/0 errors)
2.oops ~ # badblocks -s -b 4096 -c 16 /dev/sdb2 -o bad.sdb2
Checking for bad blocks (read-only test): 0.00% done, 0:22 elapsed. (0/0/0 errors)
意思就是以4k爲一個block，每一個block檢查16次，
將結果輸入到1.txt文件，如果硬盤正常的話，1.txt是沒有任何內容的，如果硬盤很大，我們可以加一個-s參數來顯示進度。
http://linux.anheng.com.cn/news/html/net_admin_blog/linux_badblocks_online_fix.html
使用badblocks 可以查出壞塊，然後badblocks本是具有寫測試功能，我們只需要用badblocks就可以了，
因爲不用向上層的文件系統提供壞道表， 所以我們在掃描壞道時，不用設置塊大小參數(-b),
首先掃描壞道
badblocks -b 4096 -o /root/sdb.bad /etc/sdb
經過慢長的時間，我們得到了一個文件/root/sdb.bad :
16435904
sdb 有1個壞塊
先用dd儘量備份壞塊
dd if=/dev/sdb bs=4096 skip=16435904 of=/tmp/15435904.dat count=1
如果顯示讀取字節數是0就多試幾次, 不行就可能丟失此塊數據, 倒是不用擔心,一般不會有太大問題.
用badblocks的寫測試功能，對這些壞塊進行重寫(注意! -w寫測試會覆蓋數據)：
badblocks -w -f /dev/sdb5 16435904 16435904
如果前面的操作有成功的備份/tmp/15435904.dat, 就把它寫回:
dd if=/tmp/15435904.dat of=/dev/sdb seek=15435904 bs=4096 count=1
其實我們不需要等待badblocks掃描完成， 就可以進行修復。
badblocks是對塊設備進行處理， 所以可以實現對掛載中的系統進行處理。
數據比硬盤值錢， 這只可以作爲臨時措施，出現壞道， 還是應該換硬盤，現在硬盤不貴。
在修復前後，利用smartctl 對磁盤進行long測試的2次結果如下：
web:~# smartctl -l selftest /dev/sdb
smartctl version 5.38 [x86_64-unknown-linux-gnu] Copyright (C) 2002-8 Bruce Allen
Home page is http://smartmontools.sourceforge.net/
=== START OF READ SMART DATA SECTION ===
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% 8308 -
# 2 Short offline Completed: read failure 10% 8292 234908935
＃2是修復前的測試 在234908935處出現讀錯誤。
#1是修復後的情況沒有錯誤
上面是對硬盤的壞塊逐塊進行修復的方式
當然可以寫一個腳本把這些命令聯起來, badblocks 也可以連續覆蓋修復壞塊 ,2個塊號的參數, 後面一個是要覆蓋的開始塊數,前面一個是結束塊數.
用smartctl對硬盤進行測試的方法如下
在線快速測試： 大約2分鐘
smartctl -t short /dev/sdb
在線長測試: (1T大約4小時)
smartctl -t long /dev/sdb
此外還有幾種測試模式:offline, short, long, conveyance, select,M-N, pending,N, afterselect,[on|off], scttempint,N[,p]
終止正在進行的測試
smartctl -X /dev/sdb
在測試結束後獲取測試結果:
smatrctl -l selftest /dev/sdb
備份壞硬盤的整盤數據：
如果用dd來備份壞硬盤的整盤數據， 千萬記住要增加 conv=noerror,sync 參數， noerror是遇到讀錯誤繼續， sync是用0填充錯誤的數據， 否則會造成數據錯位， 硬盤映像就毀了。
最好是用dd_rescue來做硬盤的dump, 能顯示當前的dump速度和平均速度。據說它還可以隨時終止， 並再次繼續，可以反向的做數據dump, 從磁盤的尾部向前dump。
在debian下，安裝ddrescue軟件包， 就可以執行dd_rescue了:
dd_rescue /dev/sdb /home/sdb.dump
在debian的新發行版中， 已經沒有dd_rescue 換成了myrescue 用法一樣
200003504
.....
240258229
(240258229-200003504)*512=20610419200b=20.61G
oops ~ # fdisk -l
Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes, 1953525168 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: 0x119af6ec
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 31459327 15728640 83 Linux
/dev/sdb2 31459328 1953525167 961032920 83 Linux
# dmesg |grep error
[14800.929308] end_request: I/O error, dev sdb, sector 1953525080
[14800.929364] end_request: I/O error, dev sdb, sector 1953525088
[14800.929423] end_request: I/O error, dev sdb, sector 1953525096
[14800.929479] end_request: I/O error, dev sdb, sector 1953525104
[14800.929535] end_request: I/O error, dev sdb, sector 1953525112
[14800.929592] end_request: I/O error, dev sdb, sector 1953525120
[14800.929648] end_request: I/O error, dev sdb, sector 1953525128
[14800.929707] end_request: I/O error, dev sdb, sector 1953525136
[14800.929762] end_request: I/O error, dev sdb, sector 1953525144
[14800.929819] end_request: I/O error, dev sdb, sector 1953525152
[14800.929876] end_request: I/O error, dev sdb, sector 1953525160
2013-11-06
debugfs: open /dev/sdb2
/dev/sdb2: Can't read an inode bitmap while reading inode bitmap
讀寫速度測試
一.寫速度測試
oops /test/nat # time dd if=/dev/zero of=/test/nat/test bs=2k count=1000000
1000000+0 records in1000000+0 records out2048000000 bytes (2.0 GB) copied, 29.6383 s, 69.1 MB/s
real 0m29.683s
user 0m0.186s
sys 0m4.672s
二.讀速度測試
oops /test/nat # time dd if=/test/nat/test of=/dev/null bs=2k1000000+0 records in1000000+0 records out2048000000 bytes (2.0 GB) copied, 1.41538 s, 1.4 GB/sreal 0m1.417suser 0m0.135s
sys 0m1.282s