One of my machines with 4 SATA disks is resyncing a sdb, which is part of a
2-way raid1 MD array with sda, but is doing so _very_ slowly at a speed of
5-10 MByte/s. The machine is idle (no CPU, no fs activity on top of the
array) and dev.raid.speed_limit_max has not been modified (left to the
default value 200000). The output of iostat doesn't make sense to me: why
are there 2-3 seconds periods of sdb being 100% utilized with an avgqu-sz
of 4 but an avgrq-sz of 0 ?! What does this mean, that 0-byte I/O requests
are being issued to the disk?
[output of essentially: iostat -x 1 /dev/sdb | grep ^sdb]
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 70.00 0.00 10.00 0.00 10240.00 1024.00
3.99 448.40 100.00 100.00
sdb 0.00 63.00 0.00 9.00 0.00 9216.00 1024.00
3.98 454.67 111.11 100.00
sdb 0.00 280.00 0.00 43.00 0.00 41344.00 961.49
2.06 36.74 15.07 64.80
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 82.00 0.00 14.00 0.00 12288.00 877.71
3.70 975.43 66.57 93.20
sdb 0.00 32.00 0.00 11.00 0.00 8120.00 738.18
1.64 426.18 72.36 79.60
sdb 0.00 0.00 0.00 2.00 0.00 136.00 68.00
0.20 164.00 102.00 20.40
sdb 0.00 117.00 0.00 15.00 0.00 13440.00 896.00
2.87 107.20 50.13 75.20
sdb 0.00 91.00 0.00 13.00 0.00 13312.00 1024.00
3.97 344.00 76.92 100.00
sdb 0.00 87.00 0.00 13.00 0.00 13312.00 1024.00
3.99 352.62 76.92 100.00
sdb 0.00 88.00 0.00 12.00 0.00 12288.00 1024.00
3.98 290.00 83.33 100.00
sdb 0.00 274.00 0.00 42.00 0.00 40448.00 963.05
2.33 37.90 17.33 72.80
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 83.00 0.00 12.00 0.00 12160.00 1013.33
3.91 1063.33 83.33 100.00
sdb 0.00 98.00 0.00 14.00 0.00 14336.00 1024.00
3.96 279.71 71.43 100.00
sdb 0.00 240.00 0.00 40.00 0.00 38400.00 960.00
2.96 88.90 20.80 83.20
sdb 0.00 75.00 0.00 8.00 0.00 8064.00 1008.00
3.62 6.00 118.00 94.40
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sdb 0.00 132.00 0.00 19.00 0.00 19328.00 1017.26
3.91 797.68 52.63 100.00
I first thought sdb was dying because svctm is often in the 50-100ms range,
when it should be less than the typical 10-20ms latency for a 7200RPM disk
given I/O ops of a max size of 512kB (avgrq-sz 1024). So I replaced it with
a brand new one but it didn't change anything. In addition, the SMART data
on the disks doesn't report anything suspicious. I can essentially
reproduce the same abysmal performance when trying to dd /dev/zero to sdb.
The 4 disks are 1.5TB Seagate 7200.11 7200RPM (ST31500341AS firmware CC1H);
they are connected to a SATA controller Broadcom BCM5785 [HT1000] (module
sata_svw) via the SATA backplane of a Tyan B3992 server; kernel is stock
2.6.31.1; arch is x86_64; motherboard is Tyan S3992; 2 Opteron 2350; 64GB
RAM.
Could the SATA backplane be the culprit? I am going to try to swap sda and
sdb, or connect sdb directly to the SATA controller, bypassing the
backplane.
$ uname -a
Linux host 2.6.31.1 #1 SMP Sat Sep 26 18:52:12 EDT 2009 x86_64 GNU/Linux
$ cat /proc/mdstat
Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4]
[raid10]
md0 : active raid1 sdc1[2] sdb1[1] sda1[0] sdd1[3]
104320 blocks [4/4] [UUUU]
md2 : active raid1 sdc5[2](F) sdd5[1]
1464734272 blocks [2/1] [_U] <-- not only sdb is slow, but sdc is
failing on this server
md1 : active raid1 sdb5[2] sda5[0]
1464734272 blocks [2/1] [U_]
[========>............] recovery = 43.5% (637657472/1464734272)
finish=1631.2min speed=8449K/sec
$ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: ST31500341AS Rev: CC1H
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: ST31500341AS Rev: CC1H
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi2 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: ST31500341AS Rev: CC1H
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi3 Channel: 00 Id: 00 Lun: 00
Vendor: ATA Model: ST31500341AS Rev: CC1H
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi4 Channel: 00 Id: 01 Lun: 00
Vendor: TEAC Model: DV-28E-N Rev: 1.6A
Type: CD-ROM ANSI SCSI revision: 05
$ dmesg
[...]
[ 4.760503] sata_svw 0000:01:0e.0: version 2.3
[ 4.760576] sata_svw 0000:01:0e.0: PCI INT A -> GSI 11 (level, low) -> IRQ
11
[ 4.760685] scsi0 : sata_svw
[ 4.760817] scsi1 : sata_svw
[ 4.760869] scsi2 : sata_svw
[ 4.760916] scsi3 : sata_svw
[ 4.760943] ata1: SATA max UDMA/133 mmio m8192@0xff4fe000 port 0xff4fe000
irq 11
[ 4.760947] ata2: SATA max UDMA/133 mmio m8192@0xff4fe000 port 0xff4fe100
irq 11
[ 4.760950] ata3: SATA max UDMA/133 mmio m8192@0xff4fe000 port 0xff4fe200
irq 11
[ 4.760953] ata4: SATA max UDMA/133 mmio m8192@0xff4fe000 port 0xff4fe300
irq 11
[...]
[ 5.081310] ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 5.116929] ata1.00: ATA-8: ST31500341AS, CC1H, max UDMA/133
[ 5.116934] ata1.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32)
[ 5.175693] ata1.00: configured for UDMA/133
[ 5.175830] scsi 0:0:0:0: Direct-Access ATA ST31500341AS CC1H
PQ: 0 ANSI: 5
[ 5.492060] ata2: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 5.529385] ata2.00: ATA-8: ST31500341AS, CC1H, max UDMA/133
[ 5.529388] ata2.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32)
[ 5.587637] ata2.00: configured for UDMA/133
[ 5.587800] scsi 1:0:0:0: Direct-Access ATA ST31500341AS CC1H
PQ: 0 ANSI: 5
[ 5.904053] ata3: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 5.939618] ata3.00: ATA-8: ST31500341AS, CC1H, max UDMA/133
[ 5.939621] ata3.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32)
[ 5.995636] ata3.00: configured for UDMA/133
[ 5.995695] scsi 2:0:0:0: Direct-Access ATA ST31500341AS CC1H
PQ: 0 ANSI: 5
[ 6.312053] ata4: SATA link up 1.5 Gbps (SStatus 113 SControl 300)
[ 6.347617] ata4.00: ATA-8: ST31500341AS, CC1H, max UDMA/133
[ 6.347630] ata4.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32)
[ 6.403640] ata4.00: configured for UDMA/133
[ 6.403796] scsi 3:0:0:0: Direct-Access ATA ST31500341AS CC1H
PQ: 0 ANSI: 5
[...]
$ lspci -s 01:0e.0 -vvv
01:0e.0 RAID bus controller: Broadcom BCM5785 [HT1000] SATA (Native SATA Mode)
(prog-if 05)
Subsystem: Broadcom BCM5785 [HT1000] SATA (Native SATA Mode)
Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR+ FastB2B-
Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort-
<TAbort- <MAbort- >SERR- <PERR-
Latency: 64
Interrupt: pin A routed to IRQ 11
Region 0: I/O ports at bc00 [size=8]
Region 1: I/O ports at b880 [size=4]
Region 2: I/O ports at b800 [size=8]
Region 3: I/O ports at b480 [size=4]
Region 4: I/O ports at b400 [size=32]
Region 5: Memory at ff4fe000 (32-bit, non-prefetchable) [size=8K]
Expansion ROM at ff4c0000 [disabled] [size=128K]
Capabilities: [60] PCI-X non-bridge device
Command: DPERE- ERO- RBC=512 OST=8
Status: Dev=01:0e.0 64bit+ 133MHz+ SCD- USC- DC=simple
DMMRBC=512 DMOST=8 DMCRS=32 RSCEM- 266MHz- 533MHz-
Capabilities: [90] Power Management version 2
Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA
PME(D0-,D1-,D2-,D3hot-,D3cold-)
Status: D0 PME-Enable- DSel=0 DScale=0 PME-
Capabilities: [a0] Message Signalled Interrupts: Mask- 64bit-
Queue=0/0 Enable-
Address: 00000000 Data: 0000
$ iostat -x 1 /dev/sd[ab]
[...]
avg-cpu: %user %nice %system %iowait %steal %idle
11.06 0.00 5.43 0.63 0.00 82.88
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 49.43 0.00 7.10 0.02 6860.66 966.90
1.57 221.51 55.89 39.66
sda 36.93 25.74 30.88 7.64 7842.26 267.14 210.53
0.60 15.64 2.38 9.17
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.00 0.00 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 162.00 0.00 24.00 0.00 22912.00 954.67
3.74 130.00 41.50 99.60
sda 121.00 0.00 61.00 0.00 23936.00 0.00 392.39
0.52 9.38 3.15 19.20
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.00 0.00 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 21.00 0.00 3.00 0.00 3072.00 1024.00
3.99 320.00 333.33 100.00
sda 15.00 0.00 9.00 0.00 3072.00 0.00 341.33
0.02 2.22 1.33 1.20
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.00 0.00 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.00 0.00 0.00 100.00
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 0.00 0.00 0.00 0.00 0.00 0.00
4.00 0.00 0.00 100.00
sda 0.00 0.00 0.00 0.00 0.00 0.00 0.00
0.00 0.00 0.00 0.00
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.10 0.00 0.00 99.90
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 159.00 0.00 25.00 0.00 23552.00 942.08
3.79 621.12 39.68 99.20
sda 127.00 0.00 57.00 0.00 23552.00 0.00 413.19
0.33 5.82 2.53 14.40
avg-cpu: %user %nice %system %iowait %steal %idle
0.00 0.00 0.20 0.00 0.00 99.80
Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz
avgqu-sz await svctm %util
sdb 0.00 334.00 0.00 51.00 0.00 50048.00 981.33
3.85 77.25 19.61 100.00
sda 256.00 0.00 134.00 0.00 49280.00 0.00 367.76
0.35 2.57 1.52 20.40
$ smartctl -a /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 INFORMATION SECTION ===
Device Model: ST31500341AS
Serial Number: (ed: removed)
Firmware Version: CC1H
User Capacity: 1,500,301,910,016 bytes
Device is: Not in smartctl database [for details use: -P showall]
ATA Version is: 8
ATA Standard is: ATA-8-ACS revision 4
Local Time is: Sat Nov 7 19:25:41 2009 EST
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: ( 0) The previous self-test routine
completed
without error or no self-test has ever
been run.
Total time to complete Offline
data collection: ( 617) 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: ( 255) minutes.
Conveyance self-test routine
recommended polling time: ( 2) minutes.
SCT capabilities: (0x103f) SCT Status 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 102 100 006 Pre-fail
Always - 5131185
3 Spin_Up_Time 0x0003 100 100 000 Pre-fail
Always - 0
4 Start_Stop_Count 0x0032 100 100 020 Old_age
Always - 3
5 Reallocated_Sector_Ct 0x0033 100 100 036 Pre-fail
Always - 0
7 Seek_Error_Rate 0x000f 100 253 030 Pre-fail
Always - 244369
9 Power_On_Hours 0x0032 100 100 000 Old_age
Always - 95
10 Spin_Retry_Count 0x0013 100 100 097 Pre-fail
Always - 0
12 Power_Cycle_Count 0x0032 100 100 020 Old_age
Always - 3
184 Unknown_Attribute 0x0032 100 100 099 Old_age
Always - 0
187 Reported_Uncorrect 0x0032 100 100 000 Old_age
Always - 0
188 Unknown_Attribute 0x0032 100 100 000 Old_age
Always - 0
189 High_Fly_Writes 0x003a 097 097 000 Old_age
Always - 3
190 Airflow_Temperature_Cel 0x0022 072 070 045 Old_age
Always - 28 (Lifetime Min/Max 23/29)
194 Temperature_Celsius 0x0022 028 040 000 Old_age
Always - 28 (0 23 0 0)
195 Hardware_ECC_Recovered 0x001a 021 021 000 Old_age
Always - 5131185
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 - 35081292873823
241 Unknown_Attribute 0x0000 100 253 000 Old_age
Offline - 2374965013
242 Unknown_Attribute 0x0000 100 253 000 Old_age
Offline - 5226517
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.
-mrb
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