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How would I monitor SSD drives SMART values? I'd like to know when the SSD is about to brick... These are the values for a Samsung 830 SSD: ID# ATTRIBUTE_

by nisa 12y ago

How would I monitor SSD drives SMART values? I'd like to know when the SSD is about to brick... These are the values for a Samsung 830 SSD: ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE 5 Reallocated_Sector_Ct PO--CK 100 100 010 - 0 9 Power_On_Hours -O--CK 097 097 000 - 13779 12 Power_Cycle_Count -O--CK 099 099 000 - 68 177 Wear_Leveling_Count PO--C- 096 096 000 - 118 179 Used_Rsvd_Blk_Cnt_Tot PO--C- 100 100 010 - 0 181 Program_Fail_Cnt_Total -O--CK 100 100 010 - 0 182 Erase_Fail_Count_Total -O--CK 100 100 010 - 0 183 Runtime_Bad_Block PO--C- 100 100 010 - 0 187 Uncorrectable_Error_Cnt -O--CK 100 100 000 - 0 190 Airflow_Temperature_Cel -O--CK 074 058 000 - 26 195 ECC_Rate -O-RC- 200 200 000 - 0 199 CRC_Error_Count -OSRCK 253 253 000 - 0 235 POR_Recovery_Count -O--C- 099 099 000 - 62 241 Total_LBAs_Written -O--CK 099 099 000 - 10945325283 Monitor all? Or just the wearlevel-count? Or watch only for the program or runtime error counts? What do these even mean?

nizmow 12y ago
I can't give you any useful information, aside from saying that I tried to work out the answers to these questions myself not long ago and the result was 'it depends'. Many of the values are manufacturer specific.
justincormack 12y ago
Most of the values count down from 100, so eg you power cycled this enough to reduce the count form 100 to 99, but it is ok until it reaches the threshold value of 0. So your drive is pretty new in terms of usage. You should run the short and long smartctl tests occasionally to get more reliable results though (smartctl -t short and smartctl -t long)
ars 12y ago
Check 177, 235 and 241. When the normalized value gets close to 0 (for any of them) start to worry. The ones I listed are the main wear indicators, for the others I'd worry if they had any value at all in the RAW column, even if the normalized value was not close to 0. If that happens then carefully research the implications of whichever one it happened to. If this is a linux server then if you configure smartmontools correctly it will email you when it gets close.
- yungchin 12y ago
  I just tried to find out about 235 (POR recovery count), and from what I gather this counts any hard power cycles you've "inflicted" on your machine, is that right? I suspect that between 177 (wear level) and 241 (blocks written), 177 may be the best indicator, because 241 may not take into account write-amplification - useful discussion of this from Anandtech: http://www.anandtech.com/show/6459/samsung-ssd-840-testing-the-endurance-of-tlc-nand http://www.anandtech.com/show/6459/samsung-ssd-840-testing-t...
jmpe 12y ago
First: I jumped into the comments before reading the article. I have quite some experience with Flash in the form of eMMC and SD/CF. SSDs aren't that much different from those on the low level. The controller that comes with the flash storage contains a core that manages the bad blocks. Comparable to bad sector management on HD. The software these controllers run contain a lot of rules of thumb to manage bad blocks, which is where these full failures come from IMO. Each controller has access to a pool of reserve blocks that are used when bad blocks are detected. Once those run out the embedded software starts showing weird behavior when using the device and shortly after there's a complete fail. I think the pool of reserve blocks is "Used_Rsvd_Blk_Cnt_Tot" in your list. Apparently there are 100, of which you consumed 0. There's a threshold at 10 so I assume that's where the diagnostics software will warn you.
- ars 12y ago
  > Apparently there are 100, of which you consumed 0. The 100 is a normalized number, it's not the actual number of blocks. (A percentage basically, so 100% are still left.) If the drive used any blocks at all I'd worry about it, I would not consider it a wear indicator but rather a failure indicator.
  - jmpe 12y ago
    > The 100 is a normalized number, it's not the actual number of blocks. I'm not too sure about that. The only ref I can give is that they use the suffix "Cnt_Tot" which means "total count". When it's a percentage they denote it as such as in "Perc_Rated_Life_Used" and "Workld_Host_Reads_Perc". Don't be surprised by the low count (100).
    - yuriks 12y ago
      That's how SMART attributes work. 100 means AOK and 0 means failed. The normalized number is reported by the drive, calculated by a formula based off the raw values and MTBF data determined by the manufacturer.
      - 12y ago
pkaye 12y ago
The ones with the "P" flags are prefail indicators that the controller manufacturer thinks will indicate failure. When value goes below threshold, it sets a SMART prefail status indicator that the host controller can poll. Unfortunately for SATA there is no way for SSD to interrupt the host controller to give such a warning so you need some kind of monitoring software to periodically poll the SMART status. Your drive looks in good shape in my opinion but thinks can always change suddenly so always backup.

by nisa 12y ago

nizmow 12y ago

I can't give you any useful information, aside from saying that I tried to work out the answers to these questions myself not long ago and the result was 'it depends'. Many of the values are manufacturer specific.

justincormack 12y ago

Most of the values count down from 100, so eg you power cycled this enough to reduce the count form 100 to 99, but it is ok until it reaches the threshold value of 0. So your drive is pretty new in terms of usage. You should run the short and long smartctl tests occasionally to get more reliable results though (smartctl -t short and smartctl -t long)

ars 12y ago

Check 177, 235 and 241. When the normalized value gets close to 0 (for any of them) start to worry. The ones I listed are the main wear indicators, for the others I'd worry if they had any value at all in the RAW column, even if the normalized value was not close to 0. If that happens then carefully research the implications of whichever one it happened to. If this is a linux server then if you configure smartmontools correctly it will email you when it gets close.

yungchin 12y ago
I just tried to find out about 235 (POR recovery count), and from what I gather this counts any hard power cycles you've "inflicted" on your machine, is that right? I suspect that between 177 (wear level) and 241 (blocks written), 177 may be the best indicator, because 241 may not take into account write-amplification - useful discussion of this from Anandtech: http://www.anandtech.com/show/6459/samsung-ssd-840-testing-the-endurance-of-tlc-nand http://www.anandtech.com/show/6459/samsung-ssd-840-testing-t...

jmpe 12y ago

First: I jumped into the comments before reading the article. I have quite some experience with Flash in the form of eMMC and SD/CF. SSDs aren't that much different from those on the low level. The controller that comes with the flash storage contains a core that manages the bad blocks. Comparable to bad sector management on HD. The software these controllers run contain a lot of rules of thumb to manage bad blocks, which is where these full failures come from IMO. Each controller has access to a pool of reserve blocks that are used when bad blocks are detected. Once those run out the embedded software starts showing weird behavior when using the device and shortly after there's a complete fail. I think the pool of reserve blocks is "Used_Rsvd_Blk_Cnt_Tot" in your list. Apparently there are 100, of which you consumed 0. There's a threshold at 10 so I assume that's where the diagnostics software will warn you.

ars 12y ago
> Apparently there are 100, of which you consumed 0. The 100 is a normalized number, it's not the actual number of blocks. (A percentage basically, so 100% are still left.) If the drive used any blocks at all I'd worry about it, I would not consider it a wear indicator but rather a failure indicator.
- jmpe 12y ago
  > The 100 is a normalized number, it's not the actual number of blocks. I'm not too sure about that. The only ref I can give is that they use the suffix "Cnt_Tot" which means "total count". When it's a percentage they denote it as such as in "Perc_Rated_Life_Used" and "Workld_Host_Reads_Perc". Don't be surprised by the low count (100).
  - yuriks 12y ago
    That's how SMART attributes work. 100 means AOK and 0 means failed. The normalized number is reported by the drive, calculated by a formula based off the raw values and MTBF data determined by the manufacturer.
    - 12y ago

pkaye 12y ago

The ones with the "P" flags are prefail indicators that the controller manufacturer thinks will indicate failure. When value goes below threshold, it sets a SMART prefail status indicator that the host controller can poll. Unfortunately for SATA there is no way for SSD to interrupt the host controller to give such a warning so you need some kind of monitoring software to periodically poll the SMART status. Your drive looks in good shape in my opinion but thinks can always change suddenly so always backup.