[kwlug-disc] SMART for SSDs

[L.D. Paniak]

With less than 800 power-on hours, this drive would have had to seen
rather aggressive continuous writes to reach the end of its endurance.
I doubt you have anything to worry about here.
Raw read error rate is generally not useful info for end users.
Reallocated sector count is probably the attribute to watch on this drive.

What make/model is this SSD?  Hard to tell if lifetime writes are LBAs
or bytes.
Maybe write 1MB of non-compressible file to the drive and see how this
value changes.  Either way you should be OK.

The analogous information for the Samsung 840 Pro in my laptop is:
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE     
UPDATED  WHEN_FAILED RAW_VALUE
  5 Reallocated_Sector_Ct   0x0033   100   100   010    Pre-fail 
Always       -       0
  9 Power_On_Hours          0x0032   099   099   000    Old_age  
Always       -       4639
 12 Power_Cycle_Count       0x0032   098   098   000    Old_age  
Always       -       1300
177 Wear_Leveling_Count     0x0013   099   099   000    Pre-fail 
Always       -       3
179 Used_Rsvd_Blk_Cnt_Tot   0x0013   100   100   010    Pre-fail 
Always       -       0
181 Program_Fail_Cnt_Total  0x0032   100   100   010    Old_age  
Always       -       0
182 Erase_Fail_Count_Total  0x0032   100   100   010    Old_age  
Always       -       0
183 Runtime_Bad_Block       0x0013   100   100   010    Pre-fail 
Always       -       0
187 Reported_Uncorrect      0x0032   100   100   000    Old_age  
Always       -       0
190 Airflow_Temperature_Cel 0x0032   070   055   000    Old_age  
Always       -       30
195 Hardware_ECC_Recovered  0x001a   200   200   000    Old_age  
Always       -       0
199 UDMA_CRC_Error_Count    0x003e   100   100   000    Old_age  
Always       -       0
235 Unknown_Attribute       0x0012   099   099   000    Old_age  
Always       -       84
241 Total_LBAs_Written      0x0032   099   099   000    Old_age  
Always       -       4381884472


Here LBAs are 512bytes.  Attribute 241 says I have written
4381884472*512B = 2.2x10^12B = 2.2TB
I would expect to get 100TB of writes on the drive before starting to worry.
The drive is rated for 300TB write.

Tests of this kind of drive have gotten over 2.4PB of writes in before
the drive quit:
http://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead


On 07/29/2015 12:52 PM, Khalid Baheyeldin wrote:
> So, I had an SSD lying around for a couple of years (long story,
> bought to benchmark against spinning rust disks for a client project).
> My laptop disk died 1.5 months ago, and when checking SMART values for
> it, it was not good.
>
> Therefore, I decided to put the SSD drive in the laptop, and copy the
> spinning drive to it. I blogged on the details of how to do that
> separately.
>
> When I run SMART on the SSD drives (smartctl --all /dev/sda), I get
> the following table:
>
> For those who have been using SSDs for a while, my question is: should
> I be worried about lines with ID 1 and 233?
>
> Vendor Specific SMART Attributes with Thresholds:
> ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE     
> UPDATED  WHEN_FAILED RAW_VALUE
>   1 Raw_Read_Error_Rate     0x0000   006   000   000    Old_age  
> Offline      -       6
>   3 Spin_Up_Time            0x0000   100   100   000    Old_age  
> Offline      -       0
>   4 Start_Stop_Count        0x0000   100   100   000    Old_age  
> Offline      -       0
>   5 Reallocated_Sector_Ct   0x0000   100   100   000    Old_age  
> Offline      -       0
>   9 Power_On_Hours          0x0000   100   100   000    Old_age  
> Offline      -       796
>  12 Power_Cycle_Count       0x0000   100   100   000    Old_age  
> Offline      -       74
> 232 Lifetime_Writes         0x0000   100   100   000    Old_age  
> Offline      -       3033270496
> 233 Media_Wearout_Indicator 0x0000   100   000   000    Old_age  
> Offline      -       100
>
> -- 
> Khalid M. Baheyeldin
> 2bits.com <http://2bits.com>, Inc.
> Fast Reliable Drupal
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