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Desktop HDD, Desktop SSHD, Barracuda, DiamondMax and other desktop SATA and
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fzabkar
Seagate's Seek Error Rate, Raw Read Error Rate, and Hardware ECC Recovered
SMART attributes
[ Edited ]
09-14-2011 11:44 PM - edited 09-15-2011 01:28 AM
Seagate's Seek Error Rate, Raw Read Error Rate, and Hardware ECC Recovered
SMART attributes create a lot of anxiety amongst Seagate users. This is
because the raw values are typically very high, and the normalised values
(Current / Worst / Threshold) are usually quite low. Despite this, the numbers
in most cases are perfectly OK.
The anxiety arises because we intuitively expect that the normalised values
should reflect a "health" score, with 100 being the ideal value. Similarly, we
would expect that the raw values should reflect an error count, in which case
a value of 0 would be most desirable. However, Seagate calculates and applies
these attribute values in a counterintuitive way.
In fact the normalised values of Seagate's Seek Error Rate, Raw Read Error
Rate, and Hardware ECC Recovered attributes are logarithmic, not linear, and
the raw values are sector counts or seek counts, not error counts.
Seagate's SMART documentation is not publicly available. The following
information has not been gleaned from any official source, but is based on my
own testing and observation, and on testing by others. Therefore it may
contain errors.
Seek Error Rate
The raw value of each SMART attribute occupies 48 bits. Seagate's Seek Error
Rate attribute consists of two parts -- a 16-bit count of seek errors in the
uppermost 4 nibbles, and a 32-bit count of seeks in the lowermost 8 nibbles. In
order to see these data, we will need a SMART utility that reports all 48 bits,
preferably in hexadecimal. Two such utilities are HD Sentinel and HDDScan.
I believe the relationship between the raw and normalised values of the SER
attribute is given by ...
normalised SER = -10 log (lifetime seek errors / lifetime seeks)
In the above formula, if the drive has recorded no errors, then we would still
need to set the number of errors to 1, otherwise the result would be
indeterminate.
The following table correlates the normalised SER against the actual error
rate:
90 = <= 1 error per 1000 million seeks
80 = <= 1 error per 100 million
70 = <= 1 error per 10 million
60 = <= 1 error per million
50 = 10 errors per million
40 = 100 errors per million
30 = 1000 errors per million
20 = 10 errors per thousand
A drive that has not yet recorded 1 million seeks will show 100 and 253 for the
Current and Worst values. I believe this is because the data are not considered
to be statistically significant until the drive has recorded 1 million seeks.
When this target is reached, the values drop to 60 and 60, assuming there have
been no errors.
By way of example, here are the SMART data for my 13GB Seagate HDD:
http://www.users.on.net/~fzabkar/SmartUDM/13GB.RPT
Attribute ID Threshold Value Worst Raw
===============================================================
Seek Error Rate 7 30 53 38 052E0E3000EC
[Mirror of full content of above URL:
SMARTUDM - HDD S.M.A.R.T. Viewer 2.00
Copyright (C) 2001-2003, Sysinfo Lab
Copyright (C) 1997, Michael Radchenko
www.sysinfolab.com e-mail: support@sysinfolab.com
HDD 1 Model: ST313021A
HDD 1 Size: 12419 Mb (12.13 Gb)
Location: Primary Master
Serial Number: 6CT0C4JE
Controller Revision: 3.03
Buffer Size: 512.0 kb
Compatibility: ATA/ATAPI-5
PIO Mode Support: 4
SW DMA Mode Support: None
MW DMA Mode Support: 2, Active: None
UDMA Mode Support: 4 (UltraDMA/66), Active: 2
Current AAM Value: None
S.M.A.R.T.: [*] enabled
SMART Self-test: [ ]
SMART Error Logging: [ ]
T.E.C. prediction monitoring started at: 31-08-07, 19:24:22
Attribute ID Threshold Value Indicator 1/Month T.E.C.
----------------------------------------------------------------------------
Raw Read Error Rate 1 0 79 ======== 0.0 Unknown
Spin Up Time 3 0 98 ========== 0.0 Unknown
* Start/Stop Count 4 20 96 ========== 0.0 Unknown
* Reallocated Sector Count 5 36 98 ========== 0.0 Unknown
* Seek Error Rate 7 30 53 ===== 0.0 Unknown
Power On Hours Count 9 0 247 ========== 0.0 Unknown
* Spin Retry Count 10 90 100 ========== 0.0 Unknown
* Drive Power Cycle Count 12 0 96 ========== 0.0 Unknown
Current Pending Sector 197 0 100 ========== 0.0 Unknown
Uncorrectable Sector 198 0 100 ========== 0.0 Unknown
UltraDMA CRC Error Rate 199 0 200 ========== 0.0 Unknown
----------------------------------------------------------------------------
NOTE: "*" means life-critical attribute
T.E.C. not detected.
Attribute ID Threshold Value Worst Raw Type
----------------------------------------------------------------------------
Raw Read Error Rate 1 0 79 78 00000753BA8Eh ER
Spin Up Time 3 0 98 97 000000000000h PR
* Start/Stop Count 4 20 96 96 000000001131h EC
* Reallocated Sector Count 5 36 98 98 000000000077h EC
* Seek Error Rate 7 30 53 38 052E0E3000ECh ER
Power On Hours Count 9 0 247 1 0000000026C7h EC
* Spin Retry Count 10 90 100 100 000000000000h EC
* Drive Power Cycle Count 12 0 96 96 00000000135Fh EC
Current Pending Sector 197 0 100 100 000000000001h EC SP
Uncorrectable Sector 198 0 100 100 000000000000h EC SP
UltraDMA CRC Error Rate 199 0 200 200 000000000000h ER
----------------------------------------------------------------------------
NOTE: "*" means life-critical attribute
Attribute types:
PR - Performance-related ER - Error rate
EC - Events count SP - Self-preserve
Reallocated Sectors: 119
Current Temperature: Not Supported
Drive Power Cycle Count: 4959
]
The number of lifetime seek errors = 0x052E (uppermost 4 nibbles)
The number of lifetime seeks = 0x0E3000EC (lowermost 8 nibbles)
Using Google's calculator ...
0x052E = 1326
0x0E3000EC = 238 026 988
http://www.google.com/search?q=0x052E+in+decimal
http://www.google.com/search?q=0x0E3000EC+in+decimal
Applying the formula ...
normalised SER = -10 log (0x052E / 0x0E3000EC)
http://www.google.com/search?q=-10+log+(0x052E+/+0x0E3000EC)
... we get a result of 52.54.
Here is a second example:
http://www.users.on.net/~fzabkar/SmartUDM/120GB.RPT
Attribute ID Threshold Value Worst Raw
===============================================================
Seek Error Rate 7 30 79 60 00000580A6AC
[Mirror of full content of above URL:
SMARTUDM - HDD S.M.A.R.T. Viewer 2.00
Copyright (C) 2001-2003, Sysinfo Lab
Copyright (C) 1997, Michael Radchenko
www.sysinfolab.com e-mail: support@sysinfolab.com
HDD 1 Model: ST3120026A
HDD 1 Size: 114473 Mb (111.79 Gb)
Location: Primary Master
Serial Number: 3JT4R9H9
Controller Revision: 8.01
Buffer Size: 8192.0 kb
Compatibility: ATA/ATAPI-6 revision 27
PIO Mode Support: 4
SW DMA Mode Support: None
MW DMA Mode Support: 2, Active: None
UDMA Mode Support: 5 (UltraDMA/100), Active: 5
Current AAM Value: 00h (80h recommended) - disabled
S.M.A.R.T.: [*] enabled
SMART Self-test: [*] enabled
SMART Error Logging: [*] enabled
T.E.C. prediction monitoring started at: 01-09-07, 09:11:00
Attribute ID Threshold Value Indicator 1/Month T.E.C.
----------------------------------------------------------------------------
* Raw Read Error Rate 1 6 64 ====== 0.0 Unknown
* Spin Up Time 3 0 96 ========== 0.0 Unknown
Start/Stop Count 4 20 100 ========== 0.0 Unknown
* Reallocated Sector Count 5 36 100 ========== 0.0 Unknown
* Seek Error Rate 7 30 79 ======== 0.0 Unknown
Power On Hours Count 9 0 99 ========== 0.0 Unknown
* Spin Retry Count 10 97 100 ========== 0.0 Unknown
Drive Power Cycle Count 12 20 100 ========== 0.0 Unknown
Drive Temperature 194 0 18 == 0.0 Unknown
Hardware ECC recovered 195 0 64 ====== 0.0 Unknown
Current Pending Sector 197 0 100 ========== 0.0 Unknown
Uncorrectable Sector 198 0 100 ========== 0.0 Unknown
UltraDMA CRC Error Rate 199 0 200 ========== 0.0 Unknown
Write Error Rate 200 0 100 ========== 0.0 Unknown
TA Counter Increased 202 0 100 ========== 0.0 Unknown
----------------------------------------------------------------------------
NOTE: "*" means life-critical attribute
T.E.C. not detected.
Attribute ID Threshold Value Worst Raw Type
----------------------------------------------------------------------------
* Raw Read Error Rate 1 6 64 62 00000AFD20E3h PR ER
* Spin Up Time 3 0 96 96 000000000000h
Start/Stop Count 4 20 100 100 000000000152h EC SP
* Reallocated Sector Count 5 36 100 100 000000000000h EC SP
* Seek Error Rate 7 30 79 60 00000580A6ACh PR ER
Power On Hours Count 9 0 99 99 0000000005DDh EC SP
* Spin Retry Count 10 97 100 100 000000000000h EC
Drive Power Cycle Count 12 20 100 100 000000000362h EC SP
Drive Temperature 194 0 18 40 000000000012h SP
Hardware ECC recovered 195 0 64 62 00000AFD20E3h ER EC
Current Pending Sector 197 0 100 100 000000000000h EC
Uncorrectable Sector 198 0 100 100 000000000000h EC
UltraDMA CRC Error Rate 199 0 200 200 000000000000h PR ER EC SP
Write Error Rate 200 0 100 253 000000000000h
TA Counter Increased 202 0 100 253 000000000000h EC SP
----------------------------------------------------------------------------
NOTE: "*" means life-critical attribute
Attribute types:
PR - Performance-related ER - Error rate
EC - Events count SP - Self-preserve
Reallocated Sectors: 0
Current Temperature: 18 C
Drive Power Cycle Count: 866
]
The above drive is in fact error free. It has recorded 0x0580A6AC seeks (= 92
million) without error.
Applying the formula ...
normalised SER = -10 log (1 / 0x0580A6AC)
... we get a result of 79.65
Note that we have used 1 instead of 0 for the error count (because log 0 is
indeterminate).
Raw Read Error Rate and Hardware ECC Recovered
The raw values of the RRER and HER attributes represent a sector count, not an
error count. This figure rolls over to 0 once the count reaches about 250
million. I suspect that the drive records the total number of errors in each
block of 250 million sectors, and then recalculates the normalised values of
each attribute accordingly. This means that RRER and HER would be updated
according to a rolling average rather than on a lifetime basis. I'm almost
certain that the normalised values are also logarithmic, but I'm not sure how
they are calculated. The above figure of 250 million sectors applies to the
7200.11 and DiamondMax 22 models, but may not apply to all.
While writing this article I came upon a Seagate document entitled "Diagnostic
Commands". It doesn't discuss SMART attributes, but it refers to "Error
Recovery Usage Rate" and defines it as ...
Error Recovery Usage Rate =
-log10 {(Number of sectors in which controller invoked specified error recovery
scheme)/[(Number of sectors transferred) * (512 bytes/sector) * (8 bits/byte)]}
This lends support for my Seek Error Rate formula, and suggests that the RRER
and HER attributes may be similarly calculated.
In fact the document mentions (but does not discuss) 5 different error recovery
schemes:
HARD = multiple retries invoked and failed
FIRM = multiple retries invoked
SOFT = 5 retries invoked
OTF = 1 retry invoked (On The Fly)
RAW = OTF ECC invoked
"On The Fly" means that errored data is corrected using the ECC bytes, without
an additional access of the platters.
Based on the abovementioned Error Recovery Usage Rate formula, I now postulate
that the normalised value of the Raw Read Error Rate attribute could be
calculated as follows:
normalised RRER = -10 log (number of errored sectors / total bits transferred)
The total number of bits is ...
(250 million sectors) x (512 bytes/sector) x (8 bits/byte) = 1.024 x 10^12
It seems to me that it makes more sense to use a round figure, say 10^12.
If we now let the number of errors equal 0 (or 1), then we have ...
max normalised RRER = -10 log (1 / 10^12) = 120
Similarly, if we let the number of errors equal 250 million (ie every sector is
errored), then we have ...
min normalised RRER = -10 log (1 / 4096) = 36
Therefore, if my hypothesis is correct, we would expect that the threshold
value of the RRER attribute would be 36, and its maximum possible value would
be 120. In fact my Internet research tends to confirm a maximum of 120 for
7200.11 models, but the threshold figure is 34.
FWIW, here are the numbers for my own Seagate drives:
Attribute ID Threshold Value Worst Raw
================================================================
Raw Read Error Rate 1 6 114 100 00000386EBBA (ST3320620A)
Raw Read Error Rate 1 6 64 62 00000AFD20E3 (ST3120026A)
Raw Read Error Rate 1 34 77 66 000007820F8F (ST340016A)
Raw Read Error Rate 1 0 79 78 00000753BA8E (ST313021A)
Hardware ECC recovered 195 0 100 63 00000C62F66E (ST3320620A)
Hardware ECC recovered 195 0 64 62 00000AFD20E3 (ST3120026A)
Hardware ECC recovered 195 0 77 66 000007820F8F (ST340016A)
http://www.users.on.net/~fzabkar/SmartUDM/320GB.RPT
http://www.users.on.net/~fzabkar/SmartUDM/120GB.RPT
http://www.users.on.net/~fzabkar/SmartUDM/40GB.RPT
http://www.users.on.net/~fzabkar/SmartUDM/13GB.RPT
References:
Here are several Usenet discussions where I have posted the results of my experiments:
Seagate - SMART Raw Read Error Rate test:
http://groups.google.com/group/comp.sys.ibm.pc.hardware.storage/browse_thread/thread/b6eb8aa2476f9ca...
SER, RRER, and HEC discussion:
http://groups.google.com/group/comp.sys.ibm.pc.hardware.storage/browse_thread/thread/54b8ad6d34549e9...
Seek Error Rate discussion:
http://groups.google.com/group/comp.sys.ibm.pc.hardware.storage/browse_thread/thread/87001db5c567fb9...
A report from a Seagate user regarding the RRER attribute:
http://forums.seagate.com/t5/Barracuda-XT-Barracuda-Barracuda/New-Maxtor-STM3500320AS-500GB-S-M-A-R-...
HD Sentinel (DOS / Windows / Linux):
http://www.hdsentinel.com/
HDDScan for Windows:
http://hddscan.com/
Explanation of SMART attributes:
http://en.wikipedia.org/wiki/S.M.A.R.T.
================================================================================
SkrewDriver
Re: Seagate's Seek Error Rate, Raw Read Error Rate, and Hardware ECC Recovered
SMART attributes
03-25-2013 11:48 AM
It looks like the SMART parameters are either misunderstood, ill-defined or the
disks don't quite know how to count. I am not sure if you still monitor this
thread, but here is an exmaple from adisk out of a Maxtor BlackArmor that
forgot its passowrd and while it is not locked, it's inaccessable to any useful
operation. HDDGuru SMART Parameters:
PHYSICAL PARAMETERS:
LBA mode is supported
LBA-48 mode is supported
Sectors available with LBA commands: 268,435,455
Sectors available with LBA48 commands: 312,581,808
Full device capacity: 160,041,885,696 bytes
SECURITY:
Security features is supported
The device is currently not locked
FEATURES:
SMART is supported
HPA (Host-protected area) is not supported
AAM (Automatic acoustic management) is not supported
Streaming feature set is not supported
QUEUING:
Command Queuing is supported by the device
Maximum Queue Depth: 32
SMART data off that same disk:
Current date and time: 3/25/2013 11:23:43
HDD Low Level Format Tool 4.12; http://hddguru.com
SMART data for [2] ST9160824AS 3.AXD [160.04 GB]
Attribute Current Worst Raw Note
----------------------------------------------------------------------------------------
1 01 Read error rate 100 253 0
3 03 Spin up time 99 98 0
4 04 Number of spin-up times 100 100 214
5 05 Reallocated sectors count 100 100 0
7 07 Seek error rate 60 57 8592033936
9 09 Power-on time 100 100 59
10 0A Spin-up retries 100 100 0
12 0C Power Cycles 100 100 244
187 BB Reported Uncorrectable 100 100 0
189 BD High Fly Writes 100 100 0
190 BE Airflow Temperature 65 45 589496355
192 C0 Power-off retract count 100 100 227
193 C1 Load/unload cycle count 100 100 981
194 C2 HDA Temperature 35 55 90194313251 (35 degrees)
195 C3 Hardware ECC recovered 118 60 171129616
197 C5 Current pending sectors 100 100 0
198 C6 Offline scan UNC sectors 100 100 0
199 C7 Ultra ATA CRC Error Rate 200 200 0
200 C8 Write error rate at preamp 100 253 0
202 CA DAM Read Errors 100 253 0
Regards,
SkrewDriver
================================================================================
fzabkar
Re: Seagate's Seek Error Rate, Raw Read Error Rate, and Hardware ECC Recovered
SMART attributes
03-26-2013 02:27 AM
Thanks for the feedback. I do keep an eye out for differences in SMART reports,
but it's difficult to make sense of all of them. That said, my predominant
focus has been on 3.5" drives, so I haven't analysed 2.5" drives to the same
extent.
The first thing you need to know is that the SMART attributes are not
standardised. They vary between manufacturers, and between models from the same
manufacturer, and even between firmware versions of the same model.
The names of the attributes are open to interpretation. The drive doesn't
report these names, only the attribute IDs. That's why different software uses
different names. For example, attribute 202 is referred to as Data Address Mark
Errors in some cases and TA Counter Increased in others. For Seagate drives, I
tend to trust HDDScan. Its author (Artem Rubtsov aka Doomer at HDD Guru) is
employed by Seagate in a data recovery capacity, so he is more likely to get
the names right.
In your SMART report, the Seek Error Rate numbers are consistent with my
analysis. In fact I have never seen any case which is an exception to the
logarithmic relationship in my article. The raw value of 8592033936 (=
0x000200200890) is reporting 2 seek errors in 2.1 million seeks.
As for read errors, your drive has no Current Pending Sectors, no Offline Scan
UNCorrectable Sectors, no Reported Uncorrectable Errors, and no Reallocated
Sectors.
The Hardware ECC Recovered looks both good and bad. That said, I'm not
completely sure how to interpret the numbers. The current value of 118 appears
to be 2 off the maximum of 120, if my interpretation of the Raw Read Error Rate
attribute in my article is correct. However, this would mean that the worst
value of 60 corresponds to 1 million errors in 250 million sectors.
In my article I refer to a Seagate document which mentions 5 different error
recovery schemes, including HARD, FIRM, SOFT, OTF, and RAW. It could be that
the Hardware ECC Recovered and Raw Read Error Rate SMART attributes refer to
different schemes in desktop and laptop drives. This could explain why the
attributes have appeared to switch places. In fact ISTR one case where the Raw
Read Error Rate attribute was referred to as "OTF errors".
One more observation I'd like to make is that there are several instances where
the worst value is 253. This appears counterintuitive since 253 is larger than
100. However, attribute values often begin life at 253 and ultimately settle
down once the drive has recorded sufficient activity for the data to be
statistically significant. You will notice that the Power On Time is still only
59 hours, so perhaps the Read Error Rate data are still not reliable.
But as I said in my article, my information is not completely reliable, and is
not based on official sources.