The primary issue relates to bad blocks / clusters and it happens to be android platform.

This is a Sandisk 128gb (leave this link - it is not an ad). Some cards indicates other problems like memory channels, write speed etc. This card I am using on an Android Nougat device.

This is the 2nd time, that the card had corruption issues. The first one I bought got write locked. I've bought a replacement. This card has a lot of bad clusters. 2 things got me to sniff this:

  • whatsApp directory (which had a bind to whatsapp dir on internal): the image directory can no longer be written to.
  • The phone randomly reboots, and next time the exFat partition is not mounted any more (I used app2sd, and partitioned the card to ext4 10gb to link my apps. The rest if exfat).

I ran a chkdksk on windows 7, and it would autoterminate on initial run & persisting on running gave me repeated message "# cluster moved for file " ( cant recollect exact verbiage ). It could Never complete it but aborted with the message . "corruption found in card "

Given this situation, is there any OS utility or 3rd party tool out there, that can complete the card run and mark the bad blocks so, that these bad blocks remain unavailable to write? Yes, I ran chkdsk with /r /x options, and that is when it puked with all these errors, and it didn't run untill end. I tried aparted for Android which runs fsck (exFat sub), and the report came normal in < 1 min which tell me it didnt invoke bad blocks routine.

From what I read due to 'wear leveling' the dynamics changes so bad sectors can't be marked permanently, and the only temporary solution would be to do a low level format. Question is - is that so , pl. confirm my understanding?

If the above is correct, I wanted to think of ways I can reduce data corruption and have a handle on the above. What I am thinking is , after erasing the data - instead of exFat. I will create several Ext4 partitions.

  • An ext4 for app2sd hidden partition (as is the case presently)
  • another ext4 pat # 2 for mostly RO data
  • ext4 pat # 3 for mostly Moderate RW data (like camera photos)
  • ext4 pat # 4 for mostly high RW ( like whatApp media)

Is this going to help make life better than before?
How do I auto mount ext4 (default external storage for Android is exFat or Fat32) and that too more than 1 partition ?
What files equivalent to fstab files in android (this is nougat) do I add my custom mount command to?
Any other solution that comes to mind?

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