经过十几个小时等待我的阵列重塑继续进行后，我认为现在终于是向您寻求一些建议的最佳时机了。
最近，我购买了第 4 个 WD Red 4TB 硬盘，将我的 3 磁盘 RAID5 设置迁移到 RAID6。所有磁盘都是 WD Red 4TB，所以我有 8TB 的可用空间。目前空间占用率为50%。
我已经安装了第四个磁盘并/dev/md0使用以下命令将其添加到：
mdadm --manage /dev/md0 --add /dev/sdf1
然后我使用以下命令开始 RAID5 到 RAID6 的迁移：
mdadm --grow /dev/md0 --level=6 --raid-disk=4
增长操作开始了，与我在互联网上发现的相比，最初的速度相当不错（例子），但 12 小时后我达到了 44k/秒，正确的是 10k/秒。外观cat /proc/mdstat如下：
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sdf1[6] sdd1[4] sda1[5] sde1[3]
7813771264 blocks super 1.2 level 6, 512k chunk, algorithm 18 [4/3] [UUU_]
[>....................] reshape = 0.1% (4931044/3906885632) finish=6498319.2min speed=10K/sec
bitmap: 8/30 pages [32KB], 65536KB chunk
unused devices: <none>
4931044在撰写此问题时，重塑过程已持续5-6 小时。
我正在使用的系统的磁盘布局如下（来自的转储lsblk）：
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 3.7T 0 disk
└─sda1 8:1 0 3.7T 0 part
└─md0 9:0 0 7.3T 0 raid6
└─vg_data-data 254:0 0 7.3T 0 lvm /data
sdb 8:16 0 55.9G 0 disk
├─sdb1 8:17 0 53.6G 0 part /
├─sdb2 8:18 0 1K 0 part
└─sdb5 8:21 0 2.3G 0 part [SWAP]
sdc 8:32 0 1.8T 0 disk
└─sdc1 8:33 0 1.8T 0 part /mnt/Backup-usb
sdd 8:48 0 3.7T 0 disk
└─sdd1 8:49 0 3.7T 0 part
└─md0 9:0 0 7.3T 0 raid6
└─vg_data-data 254:0 0 7.3T 0 lvm /data
sde 8:64 0 3.7T 0 disk
└─sde1 8:65 0 3.7T 0 part
└─md0 9:0 0 7.3T 0 raid6
└─vg_data-data 254:0 0 7.3T 0 lvm /data
sdf 8:80 0 3.7T 0 disk
└─sdf1 8:81 0 3.7T 0 part
└─md0 9:0 0 7.3T 0 raid6
└─vg_data-data 254:0 0 7.3T 0 lvm /data
为了 加快迁移速度，我在重塑运行后调整了以下参数/dev/md0：/data
sysctl -w dev.raid.speed_limit_min=100000
sysctl -w dev.raid.speed_limit_max=500000
echo 4096 > /sys/block/md0/md/stripe_cache_size
blockdev --setra 65536 /dev/md0
我还发布了echo max > /sys/block/md0/md/sync_max两次，看看它是否不会对速度产生积极影响。
我的问题是，目前重塑过程似乎陷入困境。如果dmesg | grep md0发出，会报告以下问题：
[58169.337512] md/raid:md0: raid level 6 active with 3 out of 4 devices, algorithm 18
[58169.805197] md: reshape of RAID array md0
[58169.805201] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
[58169.805203] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.
[58169.805208] md: using 128k window, over a total of 3906885632k.
[58359.078753] md/raid:md0: read error corrected (8 sectors at 9990072 on sdd1)
[58359.078758] md/raid:md0: read error corrected (8 sectors at 9990080 on sdd1)
[58359.078761] md/raid:md0: read error corrected (8 sectors at 9990088 on sdd1)
[58359.078763] md/raid:md0: read error corrected (8 sectors at 9990096 on sdd1)
[58359.078773] md/raid:md0: read error corrected (8 sectors at 9990104 on sdd1)
[58359.078774] md/raid:md0: read error corrected (8 sectors at 9990112 on sdd1)
[58359.078775] md/raid:md0: read error corrected (8 sectors at 9990120 on sdd1)
[58359.078780] md/raid:md0: read error corrected (8 sectors at 9990128 on sdd1)
[58359.078781] md/raid:md0: read error corrected (8 sectors at 9990136 on sdd1)
[58359.078791] md/raid:md0: read error corrected (8 sectors at 9990072 on sda1)
[58666.606583] Tainted: G C 3.16.0-4-amd64 #1
[58666.606721] Tainted: G C 3.16.0-4-amd64 #1
[58666.606825] Tainted: G C 3.16.0-4-amd64 #1
[58666.606948] Tainted: G C 3.16.0-4-amd64 #1
[58666.607039] Tainted: G C 3.16.0-4-amd64 #1
[58666.607148] INFO: task md0_reshape:17403 blocked for more than 120 seconds.
[58666.607168] Tainted: G C 3.16.0-4-amd64 #1
[58666.607206] md0_reshape D ffff880216d33748 0 17403 2 0x00000000
[58666.607225] [<ffffffffa0333cf2>] ? is_mddev_idle+0xd2/0x140 [md_mod]
[58666.607229] [<ffffffffa0336df4>] ? md_do_sync+0x944/0xd80 [md_mod]
[58666.607233] [<ffffffffa0333b87>] ? md_thread+0x107/0x120 [md_mod]
[58666.607238] [<ffffffffa0333a80>] ? md_stop+0x40/0x40 [md_mod]
[58786.578974] Tainted: G C 3.16.0-4-amd64 #1
[58786.579191] Tainted: G C 3.16.0-4-amd64 #1
[58786.579342] Tainted: G C 3.16.0-4-amd64 #1
[58786.579508] INFO: task md0_reshape:17403 blocked for more than 120 seconds.
[58786.579545] Tainted: G C 3.16.0-4-amd64 #1
[58786.579612] md0_reshape D ffff880216d33748 0 17403 2 0x00000000
[58786.579639] [<ffffffffa0333cf2>] ? is_mddev_idle+0xd2/0x140 [md_mod]
[58786.579644] [<ffffffffa0336df4>] ? md_do_sync+0x944/0xd80 [md_mod]
[58786.579651] [<ffffffffa0333b87>] ? md_thread+0x107/0x120 [md_mod]
[58786.579658] [<ffffffffa0333a80>] ? md_stop+0x40/0x40 [md_mod]
此外，我无法访问/data内容。如果我发出cd /data一切似乎都很好，但如果我列出内容，命令ls实际上会挂起，不返回任何结果，并迫使我终止与服务器的 ssh 会话。
我正在mdadm - v3.3.2 - 21st August 2014Debian 上运行Linux debnas 3.16.0-4-amd64 #1 SMP Debian 3.16.39-1 (2016-12-30) x86_64 GNU/Linux。
的输出iostat -k 1 2如下：
Linux 3.16.0-4-amd64 (debnas) 09/02/2019 _x86_64_ (4 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
1.25 0.00 15.25 36.91 0.00 46.59
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sdb 4.42 16.33 37.55 2191851 5038772
sda 60.00 29162.00 78.31 3913364324 10508977
sdc 0.11 0.15 0.00 19751 40
sdd 59.64 40.30 29191.39 5408213 3917308368
sde 59.97 29162.68 77.94 3913455394 10459365
sdf 0.12 0.03 36.79 4157 4936637
md0 1.79 7.45 75.01 999197 10066300
dm-0 1.71 7.44 75.01 998645 10066300
avg-cpu: %user %nice %system %iowait %steal %idle
0.50 0.00 25.00 74.50 0.00 0.00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sdb 0.00 0.00 0.00 0 0
sda 0.00 0.00 0.00 0 0
sdc 0.00 0.00 0.00 0 0
sdd 0.00 0.00 0.00 0 0
sde 0.00 0.00 0.00 0 0
sdf 0.00 0.00 0.00 0 0
md0 0.00 0.00 0.00 0 0
dm-0 0.00 0.00 0.00 0 0
更新 201909021128：当 dmesg 报告读取错误时sda，我正在发布两个驱动器sdd的完整输出。smartctl -a
user@debnas:/home/user# smartctl -a /dev/sda
smartctl 6.4 2014-10-07 r4002 [x86_64-linux-3.16.0-4-amd64] (local build)
Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Red (AF)
Device Model: WDC WD40EFRX-68N32N0
Serial Number: WD-WCC7K0YEYNV9
LU WWN Device Id: 5 0014ee 2663bb359
Firmware Version: 82.00A82
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5400 rpm
Form Factor: 3.5 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 3.1, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is: Mon Sep 2 11:27:38 2019 CEST
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: (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: (45360) 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: ( 482) minutes.
Conveyance self-test routine
recommended polling time: ( 5) minutes.
SCT capabilities: (0x303d) SCT Status supported.
SCT Error Recovery Control 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 225 163 021 Pre-fail Always - 3741
4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 66
5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0
7 Seek_Error_Rate 0x002e 100 253 000 Old_age Always - 0
9 Power_On_Hours 0x0032 100 100 000 Old_age Always - 183
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 - 66
192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 20
193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 52
194 Temperature_Celsius 0x0022 113 105 000 Old_age Always - 37
196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0
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
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
No self-tests have been logged. [To run self-tests, use: smartctl -t]
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.
user@debnas:/home/user# smartctl -a /dev/sdd
smartctl 6.4 2014-10-07 r4002 [x86_64-linux-3.16.0-4-amd64] (local build)
Copyright (C) 2002-14, Bruce Allen, Christian Franke, www.smartmontools.org
=== START OF INFORMATION SECTION ===
Model Family: Western Digital Red (AF)
Device Model: WDC WD40EFRX-68N32N0
Serial Number: WD-WCC7K2HNS0C0
LU WWN Device Id: 5 0014ee 211682e4b
Firmware Version: 82.00A82
User Capacity: 4,000,787,030,016 bytes [4.00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5400 rpm
Form Factor: 3.5 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 3.1, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is: Mon Sep 2 11:30:55 2019 CEST
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: (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: (43920) 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: ( 466) minutes.
Conveyance self-test routine
recommended polling time: ( 5) minutes.
SCT capabilities: (0x303d) SCT Status supported.
SCT Error Recovery Control 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 100 253 051 Pre-fail Always - 0
3 Spin_Up_Time 0x0027 228 200 021 Pre-fail Always - 3583
4 Start_Stop_Count 0x0032 100 100 000 Old_age Always - 8
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 100 100 000 Old_age Always - 38
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 - 8
192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 6
193 Load_Cycle_Count 0x0032 200 200 000 Old_age Always - 6
194 Temperature_Celsius 0x0022 113 104 000 Old_age Always - 37
196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0
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
SMART Error Log Version: 1
No Errors Logged
SMART Self-test log structure revision number 1
No self-tests have been logged. [To run self-tests, use: smartctl -t]
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.
更新201909021143：看来该md0_raid进程正在消耗所有CPU资源。发布后，ps aux | grep md0我可以看到 CPU 利用率为 99.7%，并且 reshape 根本不消耗 CPU：
root 17401 99.7 0.0 0 0 ? R Sep01 1348:35 [md0_raid6]
root 17403 0.0 0.0 0 0 ? D Sep01 0:04 [md0_reshape]
这些是最后几行dmesg：
[58786.579309] INFO: task postgres:5070 blocked for more than 120 seconds.
[58786.579342] Tainted: G C 3.16.0-4-amd64 #1
[58786.579371] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[58786.579409] postgres D ffff8801e2860ff8 0 5070 3818 0x00000000
[58786.579412] ffff8801e2860ba0 0000000000000082 0000000000012f40 ffff8801b4767fd8
[58786.579414] 0000000000012f40 ffff8801e2860ba0 ffff88021fa137f0 ffff88021fdbf578
[58786.579416] 0000000000000002 ffffffff8113eb70 ffff8801b4767ba0 0000000000000000
[58786.579419] Call Trace:
[58786.579421] [<ffffffff8113eb70>] ? wait_on_page_read+0x60/0x60
[58786.579424] [<ffffffff815178e9>] ? io_schedule+0x99/0x120
[58786.579426] [<ffffffff8113eb7a>] ? sleep_on_page+0xa/0x10
[58786.579429] [<ffffffff81517c6c>] ? __wait_on_bit+0x5c/0x90
[58786.579432] [<ffffffff8113e976>] ? wait_on_page_bit+0xc6/0xd0
[58786.579434] [<ffffffff810a95f0>] ? autoremove_wake_function+0x30/0x30
[58786.579437] [<ffffffff8114dc7a>] ? pagevec_lookup_entries+0x1a/0x30
[58786.579440] [<ffffffff8114e662>] ? truncate_inode_pages_range+0x302/0x5a0
[58786.579449] [<ffffffffa02efb67>] ? __ext4_journal_stop+0x37/0xa0 [ext4]
[58786.579457] [<ffffffffa02d075b>] ? ext4_rename+0x11b/0x660 [ext4]
[58786.579461] [<ffffffff811d1212>] ? __inode_wait_for_writeback+0x72/0xc0
[58786.579464] [<ffffffff812037f8>] ? __dquot_initialize+0x28/0x1c0
[58786.579467] [<ffffffff810a95f0>] ? autoremove_wake_function+0x30/0x30
[58786.579475] [<ffffffffa02c79f7>] ? ext4_evict_inode+0x127/0x4e0 [ext4]
[58786.579478] [<ffffffff811c475c>] ? evict+0xac/0x170
[58786.579481] [<ffffffff811c0548>] ? __dentry_kill+0x168/0x1d0
[58786.579484] [<ffffffff811c064e>] ? dput+0x9e/0x170
[58786.579486] [<ffffffff811b8588>] ? SYSC_renameat2+0x498/0x530
[58786.579491] [<ffffffff811719a5>] ? vm_munmap+0x45/0x50
[58786.579494] [<ffffffff8151adcd>] ? system_call_fast_compare_end+0x10/0x15
我的问题如下：
为了推动重塑进程，该怎么做？
您认为网上的数据
md0安全吗？md0如果我无法访问数据，如何访问cd？输出中的堆栈跟踪是什么
dmesg？
非常感谢您的帮助。