我正在尝试修复由 3 个 2TB 磁盘组成的 RAID5 阵列。在完美工作一段时间后，计算机（运行 Debian）突然无法再启动并卡在 GRUB 提示符下。我很确定这与 RAID 阵列有关。
由于很难全面说明已经尝试过的所有内容，因此我将尝试描述当前的状态。
mdadm --detail /dev/md0输出：
/dev/md0:
Version : 1.2
Creation Time : Sun Mar 22 15:13:25 2015
Raid Level : raid5
Used Dev Size : 1953381888 (1862.89 GiB 2000.26 GB)
Raid Devices : 3
Total Devices : 2
Persistence : Superblock is persistent
Update Time : Sun Mar 22 16:18:56 2015
State : active, degraded, Not Started
Active Devices : 2
Working Devices : 2
Failed Devices : 0
Spare Devices : 0
Layout : left-symmetric
Chunk Size : 512K
Name : ubuntu:0 (local to host ubuntu)
UUID : ae2b72c0:60444678:25797b77:3695130a
Events : 57
Number Major Minor RaidDevice State
0 0 0 0 removed
1 8 17 1 active sync /dev/sdb1
2 8 33 2 active sync /dev/sdc1
mdadm --examine /dev/sda1给出：
mdadm: No md superblock detected on /dev/sda1.
这是有道理的，因为我重新格式化了这个分区，因为我认为它是有问题的。
mdadm --examine /dev/sdb1给出：
/dev/sdb1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : ae2b72c0:60444678:25797b77:3695130a
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sun Mar 22 15:13:25 2015
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 3906764800 (1862.89 GiB 2000.26 GB)
Array Size : 3906763776 (3725.78 GiB 4000.53 GB)
Used Dev Size : 3906763776 (1862.89 GiB 2000.26 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : f1817af9:1d964693:774d5d63:bfa69e3d
Update Time : Sun Mar 22 16:18:56 2015
Checksum : ab7c79ae - correct
Events : 57
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 1
Array State : .AA ('A' == active, '.' == missing)
mdadm --detail /dev/sdc1给出：
/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : ae2b72c0:60444678:25797b77:3695130a
Name : ubuntu:0 (local to host ubuntu)
Creation Time : Sun Mar 22 15:13:25 2015
Raid Level : raid5
Raid Devices : 3
Avail Dev Size : 3906764800 (1862.89 GiB 2000.26 GB)
Array Size : 3906763776 (3725.78 GiB 4000.53 GB)
Used Dev Size : 3906763776 (1862.89 GiB 2000.26 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : f076b568:007e3f9b:71a19ea2:474e5fe9
Update Time : Sun Mar 22 16:18:56 2015
Checksum : db25214 - correct
Events : 57
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : .AA ('A' == active, '.' == missing)
cat /proc/mdstat:
Personalities : [raid6] [raid5] [raid4]
md0 : inactive sdb1[1] sdc1[2]
3906764800 blocks super 1.2
unused devices: <none>
fdisk -l:
Disk /dev/sda: 2000.4 GB, 2000398934016 bytes
81 heads, 63 sectors/track, 765633 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000d84fa
Device Boot Start End Blocks Id System
/dev/sda1 2048 3907029167 1953513560 fd Linux raid autodetect
Disk /dev/sdb: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000802d9
Device Boot Start End Blocks Id System
/dev/sdb1 * 2048 3907028991 1953513472 fd Linux raid autodetect
Disk /dev/sdc: 2000.4 GB, 2000398934016 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disk identifier: 0x000a8dca
Device Boot Start End Blocks Id System
/dev/sdc1 2048 3907028991 1953513472 fd Linux raid autodetect
Disk /dev/sdd: 7756 MB, 7756087296 bytes
255 heads, 63 sectors/track, 942 cylinders, total 15148608 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: 0x128faec9
Device Boot Start End Blocks Id System
/dev/sdd1 * 2048 15148607 7573280 c W95 FAT32 (LBA)
当然，我已经尝试/dev/sda1再次添加。mdadm --manage /dev/md0 --add /dev/sda1给出：
mdadm: add new device failed for /dev/sda1 as 3: Invalid argument
如果 RAID 已修复，我可能还需要重新启动并运行 GRUB，以便它可以检测 RAID/LVM 并再次启动。
编辑（添加 smartctl 测试结果）
smartctl测试输出
smartctl -a /dev/sda:
smartctl 6.2 2013-07-26 r3841 [x86_64-linux-3.16.0-30-generic] (local build)
Copyright (C) 2002-13, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Caviar Green (AF, SATA 6Gb/s)
Device Model: WDC WD20EZRX-00D8PB0
Serial Number: WD-WMC4M0760056
LU WWN Device Id: 5 0014ee 003a4a444
Firmware Version: 80.00A80
User Capacity: 2,000,398,934,016 bytes [2.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Device is: In smartctl database [for details use: -P show]
ATA Version is: ACS-2 (minor revision not indicated)
SATA Version is: SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Tue Mar 24 22:07:08 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: PASSED
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: ( 121) The previous self-test completed having
the read element of the test failed.
Total time to complete Offline
data collection: (26280) 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: ( 266) 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 - 3401
3 Spin_Up_Time 0x0027 172 172 021 Pre-fail Always - 4375
4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 59
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0
9 Power_On_Hours 0x0032 087 087 000 Old_age Always - 9697
10 Spin_Retry_Count 0x0032 100 253 000 Old_age Always - 0
11 Calibration_Retry_Count 0x0032 100 253 000 Old_age Always - 0
12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 59
192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 51
193 Load_Cycle_Count 0x0032 115 115 000 Old_age Always - 255276
194 Temperature_Celsius 0x0022 119 106 000 Old_age Always - 28
196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0
197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 12
198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 1
199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0
200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 1
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 Extended offline Completed: read failure 90% 9692 2057
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
您缺少 RAID5 阵列的三个驱动器之一/dev/md0。因此，mdadm将组装数组但不运行它。
-R,--run即使提供的驱动器数量少于上次阵列处于活动状态时的数量，也尝试启动阵列。通常，如果未找到所有预期的驱动器且未--scan使用该驱动器，则阵列将被组装但不会启动。无论如何都会尝试--run启动它。
所以，您需要做的就是mdadm --run /dev/md0。如果你很谨慎，你可以尝试mdadm --run --readonly /dev/md0按照它mount -o ro,norecover /dev/md0 /mnt来检查它看起来是否正常。 （--readonly当然，的反义词是--readwrite。）
一旦运行，您就可以添加回新磁盘。
我不建议添加现有磁盘，因为它会出现 SMART 磁盘错误，正如您最近的测试报告所证明的那样
SMART Self-test log structure revision number 1
Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error
# 1 Extended offline Completed: read failure 90% 9692 2057
但是，如果您确实想尝试重新添加现有磁盘，那么--zero-superblock首先添加该磁盘可能是一个好主意。但我还是建议更换。