Is my SSD failing? "Reallocated NAND Block Count" > 0

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Is my SSD failing? "Reallocated NAND Block Count" > 0

I have a Crucial CT525MX300SSD1 drive that I got in November. A third party smart utility started giving me a warning that "Reallocated NAND Block Count" indicates a failure when it went from zero to one in January. It has now gone to 4.

I downloaded Crucial Storage Executive and confirmed the "Reallocated NAND Block Count" value is 4.

But the is this a problem? I can understand a spinning magnetic surface developing defects, but why would a SSD need to reallocate blocks?

ID   Description                        Attribute Data    Units
---  --------------------------------   --------------    ----------
1    Raw Read Error Rate                             4    Errors/Page
5    Reallocated NAND Block Count                    4    NAND Blocks
9    Power On Hours Count                         1210    Hours
12   Power Cycle Count                             281    Power Cycles
171  Program Fail Count                              0    NAND Page Program Failures
172  Erase Fail Count                                0    NAND Block Erase Failures
173  Block Wear-Leveling Count                      10    Erases
174  Unexpected Power Loss Count                    58    Unexpected Power Loss events
180  Unused Reserved Block Count                  1938    Blocks
183  SATA Interface Downshift                        0    Downshifts
184  Error Correction Count                          0    Correction Events
187  Reported Uncorrectable Errors                   0    ECC Correction Failures
194  Enclosure Temperature                          25    Current Temperature (C)
                                                    39    Highest Lifetime Temperature (C)
196  Reallocation Event Count                        4    Events
197  Current Pending ECC Count                       0    ECC Counts
198  SMART Off-line Scan Uncorrectable Errors        0    Errors
199  Ultra-DMA CRC Error Count                       0    Errors
202  Percentage Lifetime Remaining                 100    % Lifetime Remaining
206  Write Error Rate                                0    Program Fails/MB
210  RAIN Successful Recovery Page Count            16    TUs successfully recovered by RAIN
246  Cumulative Host Sectors Written        4485081609    512 Byte Sectors
247  Host Program Page Count                 140654766    NAND Page
248  FTL Program Page Count                  110535820    NAND Page

1 Reply

Re: Is my SSD failing? "Reallocated NAND Block Count" > 0

It is normal for an SSD to sometimes report bad blocks during normal use as long as you don't get a lot of them in a short period of time and you still have reserve blocks available.    Getting a bad block on an SSD is not quite the same impending doom as it usually is with a traditional hard drive.    See this SSD endurance test for some interesting information about SSD failures.  


Check to make sure you are running the latest firmware on the SSD which is currently at M0CR060.   I strongly suggest updating to this version as I've had issues with earlier firmware causing the SSD to get stuck reallocating the bad blocks which then required a Secure Erase to get it working correctly again.  Looking at your SMART Attributes I don't see this happening to you yet.


I've personally encountered similar but worse problems with multiple MX300s and got them all working again so far without any further issues.




Note:  The SSD needs to be conected to an internal controller configured in AHCI mode in order to update the firmware.


Make sure to backup any data you want before doing anything just in case.  So far I have not lost any data due to a firmware update, but there is always a risk.