Max2Play Home 2016 (en) › Forums › General Questions on Hardware and Max2Play Versions › What is in this unmounted partition and what is it used for?
10. August 2019 at 16:21 #46745
I have just cloned my M2P image to a new card which is larger so I went to expand the partition but there’s an unexpected partition (Partition 3) there. What’s it for? It’s not swap, mounted, not recognised as EXT and won’t mount when manually attempted.
# fdisk -l
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 8192 93813 85622 41.8M c W95 FAT32 (LBA)
/dev/mmcblk0p2 94208 15123840 15029633 7.2G 83 Linux
/dev/mmcblk0p3 15123841 15523839 399999 195.3M 83 Linux
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
mmcblk0 179:0 0 14.9G 0 disk
├─mmcblk0p1 179:1 0 41.8M 0 part /boot
├─mmcblk0p2 179:2 0 7.2G 0 part /
└─mmcblk0p3 179:3 0 195.3M 0 part
# mount /dev/mmcblk0p3 /mnt/test/
mount: wrong fs type, bad option, bad superblock on /dev/mmcblk0p3,
missing codepage or helper program, or other error
In some cases useful info is found in syslog – try
dmesg | tail or so.
# fsck /dev/mmcblk0p3
fsck from util-linux 2.29.2
e2fsck 1.43.4 (31-Jan-2017)
ext2fs_open2: Bad magic number in super-block
fsck.ext2: Superblock invalid, trying backup blocks…
fsck.ext2: Bad magic number in super-block while trying to open /dev/mmcblk0p3
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
e2fsck -b 32768 <device>
# swapon -s
Filename Type Size Used Priority
/var/swap file 102396 0 -212. August 2019 at 15:07 #46758
So I scanned the partition and every single byte was blank. I guess that’s to be expected on an unmounted partition…
So I deleted the partition and resized using the expand filesystem function from within M2P web UI which resized it AND created the mystery partition again. I wrote the image back to the card that I had saved, resized the partition using raspi-config and no extra partition.
So this seems to be something that you have implemented that is either by design or has a bug. If it’s by design can you please elaborate what it is for? If it’s a bug, that’s in V2.48 so feel free to squash for future releases 🙂
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