总结：我使用 mdadm 进行 raid 重塑确实很慢。
完整故事：3 天前，我发现 raid 5 阵列中的一个磁盘出现故障。我将其移除并换上一个全新的磁盘。重建 12TB 阵列大约需要 8 小时，速度为 120Mb/s，一切正常。同时，我购买了另一个磁盘，将 raid 5 更新为 raid 6。重建完成后，我开始重塑，但 mdadm 非常慢，我不知道为什么，这就是我来这里的原因。
root@debian-srv:/home/debian-srv/forum# cat /proc/mdstat
Personalities : [raid6] [raid5] [raid4]
md0 : active raid6 sde[5] sdd1[4] sdb1[0] sdc1[3] sdf1[1]
11720658432 blocks super 1.2 level 6, 512k chunk, algorithm 18 [5/4] [UUUU_]
[===>.................] reshape = 17.1% (671791104/3906886144) finish=8119.0min speed=6640K/sec
unused devices: <none>
我在谷歌上读到了很多关于类似问题的文章，似乎你真的无能为力。很多人都遇到了这个问题，最终只能等待重塑完成。但我无法忍受没有关于这种行为的解释，而且如果不幸的是没有解决方案我想了解为什么会发生这种情况。
我尝试过：
- echo 50000 > /proc/sys/dev/raid/speed_limit_min
- echo 200000 > /proc/sys/dev/raid/speed_limit_max
- 回显 4096 > /sys/bloc/md0/md/stripe_cache_size
- blockdev --setra 65535 /dev/md0
- 所有驱动器的 smartctl -a
- smartctl -t 所有驱动器的缩写
- smartctl -t 为所有驱动器传送
- hdparm -tT 适用于所有驱动器
- 使用 GUI 对所有驱动器进行 SMART 测试 -> 一切正常，但 Raw_Read_Error_Rate 的数量极高（详情如下）
我没有做的事：
- 停止重塑
- 使用 GUI 执行性能测试（设备繁忙）
技术部分：这里有您可能需要的所有技术信息。
最近添加的驱动器 (sdf) 正在断断续续地写入。它写入 0.5 秒，然后停止，然后写入 0.5 秒，然后停止，等等。
Blockdev：
root@debian-srv:/home/debian-srv/forum# blockdev --getra /dev/md0
65536
root@debian-srv:/home/debian-srv/forum# blockdev --report /dev/sdb1
RO RA SSZ BSZ 1er sect. Taille Périphérique
rw 256 512 512 2048 4000785964544 /dev/sdb1
root@debian-srv:/home/debian-srv/forum# blockdev --report /dev/sdc1
RO RA SSZ BSZ 1er sect. Taille Périphérique
rw 256 512 512 2048 4000785964544 /dev/sdc1
root@debian-srv:/home/debian-srv/forum# blockdev --report /dev/sdd1
RO RA SSZ BSZ 1er sect. Taille Périphérique
rw 256 512 512 2048 4000785964544 /dev/sdd1
root@debian-srv:/home/debian-srv/forum# blockdev --report /dev/sde1
RO RA SSZ BSZ 1er sect. Taille Périphérique
rw 256 512 512 2048 4000785964544 /dev/sde1
root@debian-srv:/home/debian-srv/forum# blockdev --report /dev/sdf1
RO RA SSZ BSZ 1er sect. Taille Périphérique
rw 256 512 512 2048 4000785964544 /dev/sdf1
Hdparm -tT：
root@debian-srv:/home/debian-srv/forum# hdparm -tT /dev/sdb1
/dev/sdb1:
Timing cached reads: 2284 MB in 2.00 seconds = 1142.10 MB/sec
Timing buffered disk reads: 416 MB in 3.00 seconds = 138.61 MB/sec
root@debian-srv:/home/debian-srv/forum# hdparm -tT /dev/sdc1
/dev/sdc1:
Timing cached reads: 2318 MB in 2.00 seconds = 1158.86 MB/sec
Timing buffered disk reads: 422 MB in 3.01 seconds = 140.31 MB/sec
root@debian-srv:/home/debian-srv/forum# hdparm -tT /dev/sdd1
/dev/sdd1:
Timing cached reads: 2228 MB in 2.00 seconds = 1114.15 MB/sec
Timing buffered disk reads: 406 MB in 3.02 seconds = 134.46 MB/sec
root@debian-srv:/home/debian-srv/forum# hdparm -tT /dev/sde1
/dev/sde1:
Timing cached reads: 2238 MB in 2.00 seconds = 1117.17 MB/sec
Timing buffered disk reads: 326 MB in 3.00 seconds = 108.53 MB/sec
root@debian-srv:/home/debian-srv/forum# hdparm -tT /dev/sdf1
/dev/sdf1:
Timing cached reads: 2290 MB in 2.00 seconds = 1144.44 MB/sec
Timing buffered disk reads: 240 MB in 3.01 seconds = 79.70 MB/sec
消息：
[ 568.432282] md/raid:md0: raid level 5 active with 3 out of 4 devices, algorithm 2
[ 568.432287] RAID conf printout:
[ 568.432291] --- level:5 rd:4 wd:3
[ 568.432295] disk 0, o:1, dev:sdb1
[ 568.432299] disk 1, o:1, dev:sdf1
[ 568.432303] disk 2, o:1, dev:sdc1
[ 568.432376] md0: detected capacity change from 0 to 12001954234368
[ 568.437054] md0: unknown partition table
[ 942.055088] sde: sde1
[ 943.061844] sde: sde1
[ 954.016396] sde: sde1
[ 954.096613] sde: sde1
[ 954.339219] sde:
[ 956.007038] sde:
[ 956.897606] sde:
[ 1084.011243] sdd: sdd1
[ 1090.191545] md: bind<sdd1>
[ 1090.994243] RAID conf printout:
[ 1090.994254] --- level:5 rd:4 wd:3
[ 1090.994261] disk 0, o:1, dev:sdb1
[ 1090.994266] disk 1, o:1, dev:sdf1
[ 1090.994270] disk 2, o:1, dev:sdc1
[ 1090.994274] disk 3, o:1, dev:sdd1
[ 1090.994533] md: recovery of RAID array md0
[ 1090.994562] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
[ 1090.994567] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for recovery.
[ 1090.994583] md: using 128k window, over a total of 3906886144k.
[34484.341520] **perf interrupt took too long (2504 > 2500), lowering kernel.perf_event_max_sample_rate to 50000**
[37107.251863] md: md0: recovery done.
[37107.335417] RAID conf printout:
[37107.335425] --- level:5 rd:4 wd:4
[37107.335431] disk 0, o:1, dev:sdb1
[37107.335435] disk 1, o:1, dev:sdf1
[37107.335439] disk 2, o:1, dev:sdc1
[37107.335443] disk 3, o:1, dev:sdd1
[39462.786459] sde:
[39463.780907] sde:
[39549.892683] sde:
[39550.012102] sde: sde1
[39550.457721] sde: sde1
[39564.176984] sde: sde1
[39583.200701] sde: sde1
[39583.389783] sde:
[39584.746260] sde:
[39585.685914] sde:
[39599.583805] sde:
[39688.406254] sde: sde1
[39689.551676] sde: sde1
[39731.259332] sde: sde1
[39731.292927] md: bind<sde>
[39732.115520] RAID conf printout:
[39732.115530] --- level:5 rd:4 wd:4
[39732.115537] disk 0, o:1, dev:sdb1
[39732.115542] disk 1, o:1, dev:sdf1
[39732.115547] disk 2, o:1, dev:sdc1
[39732.115551] disk 3, o:1, dev:sdd1
[40062.994054] md/raid:md0: device sdd1 operational as raid disk 3
[40062.994065] md/raid:md0: device sdb1 operational as raid disk 0
[40062.994070] md/raid:md0: device sdc1 operational as raid disk 2
[40062.994075] md/raid:md0: device sdf1 operational as raid disk 1
[40062.994908] md/raid:md0: allocated 0kB
[40062.997006] md/raid:md0: raid level 6 active with 4 out of 5 devices, algorithm 18
[40062.997012] RAID conf printout:
[40062.997016] --- level:6 rd:5 wd:4
[40062.997021] disk 0, o:1, dev:sdb1
[40062.997025] disk 1, o:1, dev:sdf1
[40062.997029] disk 2, o:1, dev:sdc1
[40062.997033] disk 3, o:1, dev:sdd1
[40063.938537] RAID conf printout:
[40063.938548] --- level:6 rd:5 wd:4
[40063.938555] disk 0, o:1, dev:sdb1
[40063.938560] disk 1, o:1, dev:sdf1
[40063.938564] disk 2, o:1, dev:sdc1
[40063.938568] disk 3, o:1, dev:sdd1
[40063.938572] disk 4, o:1, dev:sde
[40063.939415] md: reshape of RAID array md0
[40063.939420] md: minimum _guaranteed_ speed: 1000 KB/sec/disk.
[40063.939425] md: using maximum available idle IO bandwidth (but not more than 200000 KB/sec) for reshape.
[40063.939444] md: using 128k window, over a total of 3906886144k.
在 dmesg 中以粗体显示：perf 中断耗时过长 (2504 > 2500)，将 kernel.perf_event_max_sample_rate 降低至 50000
伊诺斯塔特：
root@debian-srv:/home/debian-srv/forum# iostat -k 1 2
Linux 3.16.0-4-686-pae (debian-srv) 15/01/2016 _i686_ (1 CPU)
avg-cpu: %user %nice %system %iowait %steal %idle
1,57 0,01 16,86 62,84 0,00 18,71
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sdc 97,10 7314,85 5138,04 955775539 671347807
sde 23,55 9,64 5140,51 1259429 671671477
sdb 97,44 7338,30 5138,04 958839263 671348371
sdd 105,10 10284,96 2169,18 1343857318 283429894
sdf 178,44 7311,34 5138,03 955317427 671347771
sda 34,57 9,86 15444,98 1288209 2018077322
md0 5,84 23,40 0,12 3057188 15908
avg-cpu: %user %nice %system %iowait %steal %idle
1,01 0,00 17,17 81,82 0,00 0,00
Device: tps kB_read/s kB_wrtn/s kB_read kB_wrtn
sdc 56,57 14480,81 8277,27 14336 8194
sde 37,37 0,00 8277,27 0 8194
sdb 55,56 14480,81 8277,27 14336 8194
sdd 56,57 14480,81 8277,27 14336 8194
sdf 92,93 14480,81 8277,27 14336 8194
sda 37,37 0,00 16072,73 0 15912
md0 0,00 0,00 0,00 0 0
麦达明：
root@debian-srv:/home/debian-srv/forum# mdadm --detail /dev/md0
/dev/md0:
Version : 1.2
Creation Time : Thu Dec 11 18:42:03 2014
Raid Level : raid6
Array Size : 11720658432 (11177.69 GiB 12001.95 GB)
Used Dev Size : 3906886144 (3725.90 GiB 4000.65 GB)
Raid Devices : 5
Total Devices : 5
Persistence : Superblock is persistent
Update Time : Fri Jan 15 13:06:29 2016
State : clean, degraded, reshaping
Active Devices : 4
Working Devices : 5
Failed Devices : 0
Spare Devices : 1
Layout : left-symmetric-6
Chunk Size : 512K
Reshape Status : 17% complete
New Layout : left-symmetric
Name : debian-srv:0 (local to host debian-srv)
UUID : f223d47d:882f9fdc:be7c8169:864feca4
Events : 718531
Number Major Minor RaidDevice State
0 8 17 0 active sync /dev/sdb1
1 8 81 1 active sync /dev/sdf1
3 8 33 2 active sync /dev/sdc1
4 8 49 3 active sync /dev/sdd1
5 8 64 4 spare rebuilding /dev/sde
/proc/sys/dev/raid/speed_limit_* 和 /sys/block/md0/md/sync_speed_*：
root@debian-srv:/home/debian-srv/forum# cat /proc/sys/dev/raid/speed_limit_max
200000
root@debian-srv:/home/debian-srv/forum# cat /proc/sys/dev/raid/speed_limit_min
50000
root@debian-srv:/home/debian-srv/forum# cat /sys/block/md0/md/sync_speed_min
200000 (local)
root@debian-srv:/home/debian-srv/forum# cat /sys/block/md0/md/sync_speed_max
200000 (system)
条带缓存大小：
root@debian-srv:/home/debian-srv/forum# cat /sys/block/md0/md/stripe_cache_size
4096
设备队列：
root@debian-srv:/home/debian-srv/forum# cat /sys/block/sdb/device/queue_*
31
120000
simple
root@debian-srv:/home/debian-srv/forum# cat /sys/block/sdc/device/queue_*
31
120000
simple
root@debian-srv:/home/debian-srv/forum# cat /sys/block/sdd/device/queue_*
31
120000
simple
root@debian-srv:/home/debian-srv/forum# cat /sys/block/sde/device/queue_*
1
none
root@debian-srv:/home/debian-srv/forum# cat /sys/block/sdf/device/queue_*
1
none
Smartctl-a：
root@debian-srv:/home/debian-srv/forum# smartctl -a /dev/sdc
=== START OF INFORMATION SECTION ===
Model Family: Seagate Desktop HDD.15
Device Model: ST4000DM000-1F2168
Serial Number: Z301XYMT
LU WWN Device Id: 5 000c50 067546e57
Firmware Version: CC52
User Capacity: 4 000 787 030 016 bytes [4,00 TB]
Sector Sizes: 512 bytes logical, 4096 bytes physical
Rotation Rate: 5900 rpm
Form Factor: 3.5 inches
Device is: In smartctl database [for details use: -P show]
ATA Version is: ATA8-ACS T13/1699-D revision 4
SATA Version is: SATA 3.1, 6.0 Gb/s (current: 3.0 Gb/s)
Local Time is: Fri Jan 15 12:05:29 2016 CET
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
...
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 119 099 006 Pre-fail Always - 214628264
3 Spin_Up_Time 0x0003 091 091 000 Pre-fail Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age Always - 15
5 Reallocated_Sector_Ct 0x0033 100 100 010 Pre-fail Always - 0
7 Seek_Error_Rate 0x000f 071 060 030 Pre-fail Always - 13940971
9 Power_On_Hours 0x0032 090 090 000 Old_age Always - 8769
10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail Always - 0
12 Power_Cycle_Count 0x0032 100 100 020 Old_age Always - 15
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 100 100 000 Old_age Always - 0 0 0
189 High_Fly_Writes 0x003a 097 097 000 Old_age Always - 3
190 Airflow_Temperature_Cel 0x0022 066 057 045 Old_age Always - 34 (Min/Max 31/36)
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 - 6
193 Load_Cycle_Count 0x0032 100 100 000 Old_age Always - 18
194 Temperature_Celsius 0x0022 034 043 000 Old_age Always - 34 (0 15 0 0 0)
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 - 8769h+51m+55.474s
241 Total_LBAs_Written 0x0000 100 253 000 Old_age Offline - 27801843844
242 Total_LBAs_Read 0x0000 100 253 000 Old_age Offline - 68841105748
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 Short offline Completed without error 00% 8768 -
# 2 Conveyance offline Completed without error 00% 8728 -
# 3 Short offline Completed without error 00% 8728 -
# 4 Short offline Completed without error 00% 0 -
结论：我跑了smartctl-a在所有设备上，但我无法向您显示完整结果（主体长度限制）。如有需要，请提出要求。任何帮助都将不胜感激！
谢谢你们 ！
编辑：好的，当然，因为墨菲是我的朋友，所以我在重塑过程中遇到了电源故障。
好的伙计们，对于下一个面临同样问题的人，这里是解决方案：
没有解决办法！
就这样。速度很慢，好吧，接受吧，就这样。
然而，正如我在第一篇帖子的结尾所说的那样，我在重塑过程中遇到了电源故障（Murrrphyyyyyyy），但多亏了这一点，我可以确认可以安全地停止重塑。 如果你遇到同样的问题，你可以停止重塑过程并检查你的 SATA 线。事实上，我在另一篇文章中看到有人遇到了同样的问题，而且是 SATA 电缆，所以我趁着断电的机会检查了我的电缆，其中一根电缆确实状况不佳（塑料部分损坏）。我更换了它，重新启动了重塑，速度变快了（大约 40Mb/s）
答案1
如果有人像我一样最终到达这里，这个命令将使同步进入高速运转：
echo max | sudo tee /sys/block/md0/md/sync_max
答案2
我认为您的 stripe_cache_size 太小了。我的 raid6 有 6 个磁盘，速度也很慢，我将 stripe_cache_size 增加到 32000。如果我没记错的话，这是最大的了。
答案3
我看到您的存储集已降级，并且备用驱动器上没有分区。就我而言，我添加了一个磁盘，现在有 4 个成员，状态为正在重塑，但没有降级。我没有备用磁盘。我使用磁盘上的分区来应对将来不同的磁盘大小。我的重塑也非常慢。（4x2TB 需要 6 天）
答案4
您可以将 ncq 设置为 1。此操作在我的案例中额外提高了约 30% 的速度（将 raid5 从 9 个磁盘重塑为 10 个磁盘）：从约 30Mb/s 提高到约 40Mb/s。
for dev in $(mdadm --detail /dev/md2|sed '/active sync/!d;s|.*/dev/\([^0-9]*\).*|\1|'); do
echo -n "$dev: $(cat /sys/block/$dev/device/queue_depth) -> "
echo 1 > /sys/block/$dev/device/queue_depth
cat /sys/block/$dev/device/queue_depth
done