To sum up : My raid reshape with mdadm is really slow.
The complete story : 3 days ago I realized that one of my disks from a raid 5 array was faulty. I removed it and replaced it with a brand new one. The rebuild took approximately 8 hours for a 12TB array at 120Mb/s, everything was fine. At the same time I bought another disk to update my raid 5 to raid 6. When the rebuild finished I started a reshape, but mdadm is reeeaaaally slow and I didn't figure out why that's why I'm here.
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>
I read a lot on google about similar issue, and it seems that you can't really do something about it. A lot of people ran into this problem and eventually wait for the reshape to complete. But I can't stand there is no exaplanation about this behaviour, and if unfortunately there is no solution I would like to understand why it's happening.
What I tried :
- echo 50000 > /proc/sys/dev/raid/speed_limit_min
- echo 200000 > /proc/sys/dev/raid/speed_limit_max
- echo 4096 > /sys/bloc/md0/md/stripe_cache_size
- blockdev --setra 65535 /dev/md0
- smartctl -a for all drives
- smartctl -t short for all drives
- smartctl -t conveyance for all drives
- hdparm -tT for all drives
- S.M.A.R.T test with the GUI for all drives -> everything is OK but the number of Raw_Read_Error_Rate is extremely high (details below)
What I didn't do:
- Stop the reshape
- Perform a performance test with the gui (device busy)
The technical part: Here is all the technical informations you may need.
The recently added drive (sdf) is writting fitfully. It writes for 0.5s, then stop, then writes for 0.5s, then stop etc.
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
Dmesg:
[ 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.
In bold in dmesg I have : perf interrupt took too long (2504 > 2500), lowering kernel.perf_event_max_sample_rate to 50000
Iostat :
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
Mdadm :
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_* and /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)
Stripe_cache_size:
root@debian-srv:/home/debian-srv/forum# cat /sys/block/md0/md/stripe_cache_size
4096
Device queue:
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 -
Conclusion: I ran smartctl -a on all devices but I can't show you the full results (body length limit). Ask for it if needed. Any help is appreciated !
Thank you all !
Edit: Ok so of course since Murphy is my friend I had a power failure during the reshape.
Ok guys, so for the next one facing the same problem here is the solution :
There is no solution !
That's all. It's slow, ok deal with it, that's all.
However, as I said at the end of my first post, I had a power failure during the reshape (Murrrphyyyyyyy), but thanks to that I can confirm that it's safe to stop a reshape. If you encounter the same problem, you can stop the reshaping process and check your sata cable. In fact, I read on another post that someone faced the same issue and it was a SATA cable, so I took the opportunity of the power failure to check my cables, and one of them was actually in bad shape (plastic part broken). I replaced it, restarted the reshape and it went quicker (around 40Mb/s)
