MFS on MQX 4.2: Both FAT16 tables full of erroneous FFFF entries

[richi235]

Hi folks,
I'm getting the following problem on several devices:

After around 1.5 years of usage the 1 GB SD card reports "full" however, when we look at the filesystem more precisely only around 40 MB in the Data region are used (around 300 files). But the 2 fat tables are full of FF FF entries (which is also CLUSTER_EOF in the MFS source code, i.e. the fat16 end of chain marker entry).

Those FF FF entries start at cluster number 2528 (which is after all of our "proper data clusters") are written cleanly until the end of the fat table, then comes the 00 00 padding until the end of the sector. This is also exactly the same in the second fat table, which leads me to believe it was done by something that understands the FAT tables, (like MFS).

Does anyone have any ideas? Or had something like this before? Any help or hint is appreciated

Thanks in advance,
-- Richard

[richi235]

 A few little extra infos:

• When compressed the whole image of the SD card is still only around 40 MB
• I've checked the whole image with a FAT16 recovery tool and found nothing
• Our cluster size is 32 sectors, i.e. 16 KB (with 512 byte sectors)
• I found out FF FF can also be the entry for a small file (< cluster size) so this bug could be thousands of small file, however as the recovery tool found nothing, I'm not convinced of that thesis anymore. The data region seems mostly untouched

[danielchen]

Hi @richi235 

Did you apply the patch MQX 4.2.0.2 ?  

Regards

Daniel