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Ubuntu 13.04. The number of bad sectors on my SSD has steadily increased until 226 bad sectors today.

The thing is, I don't know whether 226 bad sectors is 0.0001% of the SSD, 1% of the SSD, or 99% of the SSD.

I haven't found anything on the internet this morning to answer this question.

The Disks utility doesn't tell me either, and I can't find the information in SMART Data.

sudo smartctl -a /dev/sda shows this:

smartctl 5.43 2012-06-30 r3573 [x86_64-linux-3.8.0-31-generic] (local build)
Copyright (C) 2002-12 by Bruce Allen,

Device Model:     Samsung SSD 840 PRO Series
Serial Number:    S1ATNEAD645474H
LU WWN Device Id: 5 002538 5503c15c0
Firmware Version: DXM05B0Q
User Capacity:    256,060,514,304 bytes [256 GB]
Sector Size:      512 bytes logical/physical
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   8
ATA Standard is:  ATA-8-ACS revision 4c
Local Time is:    Fri Jan 24 20:37:08 2014 CST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

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:                (53956) seconds.
Offline data collection
capabilities:                    (0x53) SMART execute Offline immediate.
                                        Auto Offline data collection on/off support.
                                        Suspend Offline collection upon new
                                        No Offline surface scan supported.
                                        Self-test supported.
                                        No 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:        (  20) minutes.
SCT capabilities:              (0x003d) SCT Status supported.
                                        SCT Error Recovery Control supported.
                                        SCT Feature Control supported.
                                        SCT Data Table supported.

SMART Attributes Data Structure revision number: 1
Vendor Specific SMART Attributes with Thresholds:
  5 Reallocated_Sector_Ct   0x0033   097   097   010    Pre-fail  Always       -       238
  9 Power_On_Hours          0x0032   099   099   000    Old_age   Always       -       1331
 12 Power_Cycle_Count       0x0032   099   099   000    Old_age   Always       -       341
177 Wear_Leveling_Count     0x0013   097   097   000    Pre-fail  Always       -       75
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   097   097   010    Pre-fail  Always       -       238
181 Program_Fail_Cnt_Total  0x0032   097   097   010    Old_age   Always       -       238
182 Erase_Fail_Count_Total  0x0032   100   100   010    Old_age   Always       -       0
183 Runtime_Bad_Block       0x0013   097   097   010    Pre-fail  Always       -       238
187 Reported_Uncorrect      0x0032   100   100   000    Old_age   Always       -       0
190 Airflow_Temperature_Cel 0x0032   067   062   000    Old_age   Always       -       33
195 Hardware_ECC_Recovered  0x001a   200   200   000    Old_age   Always       -       0
199 UDMA_CRC_Error_Count    0x003e   099   099   000    Old_age   Always       -       1
235 Unknown_Attribute       0x0012   099   099   000    Old_age   Always       -       128
241 Total_LBAs_Written      0x0032   099   099   000    Old_age   Always       -       33308592070

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
    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
  255        0    65535  Read_scanning was never started
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.
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Did you check this? Try sudo badblocks -v /dev/sda in the command line – mcantsin Jan 23 '14 at 0:55
Disks utility reports 227 bad sectors this afternoon (after about 8 hours since I posted this question), and the accompanying SMART Data says 183 runtime-bad-block-total 227 OK. Knowing that, it's not so bad since 227/250059095=0.000000908 | In reply to the question from @mcantsin: sudo badblocks -v /dev/sda gives Checking blocks 0 to 250059095 Checking for bad blocks (read-only test): done Pass completed, 0 bad blocks found. (0/0/0 errors) which hopefully is a good thing. – el_gallo_azul Jan 23 '14 at 7:52
@user91583 Please add the output of sudo smartctl -a /dev/sda to your question. (Or if your SSD is not /dev/sda then change that command accordingly.) – falconer Jan 23 '14 at 12:51
@el_gallo_azul Then first install it by running sudo apt-get install smartmontools . – falconer Jan 24 '14 at 7:03
@falconer sudo smartctl -a /dev/sda now gives (I hope this link works for you. Let me know if it doesn't). – el_gallo_azul Jan 24 '14 at 11:20

The smart data of our SSD says that you used the SSD for 1331 hours and your SSD has suffered 33308592070*512/1024^4=15,5 TiB writes. That means ca. 12 GiB writes per power on hours on your SSD. That is kinda lot for a typical consumer SSD usage. What do you use the SSD for?

You are still way below the write cycle limit of your SSD, which is an MLC based one, so should tolerate ca. 3000 write cycles, which would mean ca. 256GB*3000=768 TB writes. So I would say you are safe.

But your SMART data shows that now you have already 238 reallocated (failed) sectors. That number is still very low compared to the few hundred million sectors on your drive, but for me it is surprising that after only 60-70 write cycles your SSD has failing blocks. Do you have some spare space on your SSD? The SSDs needs some spare space to be able to efficiently manage the wear on the drive. If the drive is almost full it wears faster because of the increased writes of the wear leveling algorithm.

Here is a graph showing a 840 PRO 256 GB SSD under write test. It has still zero, or very close to zero reallocated sectors after 300 TB writes. You have more than 200 after less than 20 TB.

You are using the latest firmware of the drive. I don't want to worry you but I think you should contact Samsung with that SMART output, and ask about their opinion. I think your drive has some kind of problem.


After Samsung's response - who basically said everything is fine - I would say that as long as you don't encounter data loss, (that is as long as the badblocks discovered during a write operation) I think you shouldn't worry then.

You can see the badblock count in the Runtime_bad_block line (238, the Raw value) that is the sum of the Program_Fail_Cnt_Total (238, which is the failed write operations) the Erase_Fail_Count_Total (0, which is the failed erase operations) and the failed read operations. So the failed read operations on your drive at the time the smart output was generated is 238-238-0=0, so you didn't have any failed read, you don't have any data loss.

If your drive starts to encounter failed reads too in the near future (that means the Runtime_bad_block will not equal Program_Fail_Cnt_Total + Erase_Fail_Count_Total), potential data loss, I would recontact Samsung. Until that time just enjoy your SSD.

share|improve this answer
I use BOINC and I also let the SkyNet Java client run in multiple instances in the background. Yes I let it do very much writing in this process, and I am trying to find a way to get both of these to use the HDD instead of the SSD. On the spare space matter, my SSD is 25% used, and I will limit its use to 70% if I can - so far, so good. That's interesting about the performance of my SSD against Samsung benchmarks. I will follow that one up if I am able. – el_gallo_azul Jan 25 '14 at 2:09
@el_gallo_azul I found an updated version of that test which I linked in my answer, here it is. It says explicitly the numbers after 500 TB: The 840 Pro, which has recorded only two reallocated sectors and no unrecoverable errors, has the same "good" health rating. So after 500 TB writes the same model as yours had only 2 reallocated sectors, you have more than a hundred times of that after less than 20TB. I would definitely send an email to Samsung with your SMART data and ask their opinion. It won't hurt. – falconer Jan 27 '14 at 9:18
I just sent the information via webform to Samsung. I intend to post a summary of the Samsung response here if I receive one. Thanks for your help. – el_gallo_azul Jan 28 '14 at 3:50
First response from Samsung on 29.01.2014: "You want to know why would you have many times more reallocated sectors in your Samsung 256GB SSD PRO 840 Series. Please be advised that we forwarded this concern to the relevant department and we will contact you once update becomes available." – el_gallo_azul Jan 30 '14 at 2:32
@el_gallo_azul Thanks for keeping us updated. I'm interested in Samsung's response. – falconer Jan 30 '14 at 8:45
up vote 0 down vote accepted

It eventuated that that Samsung 840 Pro SSD had a catastrophic failure later in 2014. It was replaced under warranty with the Samsung 850 Pro, which has now been running successfully since then, and still does not report any bad sectors. I'm pleased about that, because I thought maybe it was an "undocumented feature" of SSDs.

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