[Android Q&A, Help & Troubleshooting] Shambler0:
VOLD seems to ignore partition number specified in vold.fstab:

Stock vold.fstab:

dev_mount sdcard /mnt/sdcard [COLOR="Red"][B]auto [/B][/COLOR]/devices/platform/msm_sdcc.3/mmc_host

I changed it to:

dev_mount sdcard /mnt/sdcard [COLOR="Red"][B]21 [/B][/COLOR]/devices/platform/msm_sdcc.3/mmc_host

But VOLD still tries to mount partition No 20 (the stock partition meant for sdcard, which is now formatted as EXT4) and fails.

logcat output:

I/Vold ( 124): Vold 2.1 (the revenge) firing up
D/Vold ( 124): Volume sdcard state changing -1 (Initializing) -> 0 (No-Media)
D/Vold ( 124): Volume extsdcard state changing -1 (Initializing) -> 0 (No-Media)
D/Vold ( 124): Volume sdcard state changing 0 (No-Media) -> 1 (Idle-Unmounted)
W/Vold ( 124): Duplicate state (1)
W/Vold ( 124): Ignoring unknown switch 'usb_mass_storage'
W/Vold ( 124): Ignoring unknown switch 'usb_connected'
D/Vold ( 124): USB disconnected
D/Vold ( 124): Share method ums now unavailable
W/Vold ( 124): Ignoring unknown switch 'MSM72K_UDC'
W/Vold ( 124): Ignoring unknown switch 'usb_connected'
W/Vold ( 124): Ignoring unknown switch 'usb_mass_storage'
W/Vold ( 124): Ignoring unknown switch 'MSM72K_UDC'
D/Vold ( 124): USB connected
D/Vold ( 124): Share method ums now available
D/VoldCmdListener( 124): volume list
D/VoldCmdListener( 124): share status ums
D/VoldCmdListener( 124): share status ums
D/VoldCmdListener( 124): volume mount /mnt/sdcard
D/Vold ( 124): partNode : 0xb314
E/Vold ( 124): no need to check the rest of partitions, skip : 23
E/Vold ( 124): no need to check the rest of partitions, skip : 22
E/Vold ( 124): no need to check the rest of partitions, skip : 21
I/Vold ( 124): /dev/block/vold/179:20 being considered for volume sdcard
D/Vold ( 124): Volume sdcard state changing 1 (Idle-Unmounted) -> 3 (Checking)
E/Vold ( 124): Filesystem check failed (not a FAT filesystem)
W/Vold ( 124): /dev/block/vold/179:20 does not contain a FAT filesystem
E/Vold ( 124): no need to check the rest of partitions, skip : 19
E/Vold ( 124): no need to check the rest of partitions, skip : 18
E/Vold ( 124): no need to check the rest of partitions, skip : 17
E/Vold ( 124): no need to check the rest of partitions, skip : 16
E/Vold ( 124): no need to check the rest of partitions, skip : 15
E/Vold ( 124): no need to check the rest of partitions, skip : 14
E/Vold ( 124): no need to check the rest of partitions, skip : 13
E/Vold ( 124): no need to check the rest of partitions, skip : 12
E/Vold ( 124): no need to check the rest of partitions, skip : 11
E/Vold ( 124): no need to check the rest of partitions, skip : 10
E/Vold ( 124): no need to check the rest of partitions, skip : 9
E/Vold ( 124): no need to check the rest of partitions, skip : 8
E/Vold ( 124): no need to check the rest of partitions, skip : 7
E/Vold ( 124): no need to check the rest of partitions, skip : 6
E/Vold ( 124): no need to check the rest of partitions, skip : 5
E/Vold ( 124): no need to check the rest of partitions, skip : 4
E/Vold ( 124): no need to check the rest of partitions, skip : 3
E/Vold ( 124): no need to check the rest of partitions, skip : 2
E/Vold ( 124): no need to check the rest of partitions, skip : 1
E/Vold ( 124): no need to check the rest of partitions, skip : 0
E/Vold ( 124): Volume sdcard found no suitable devices for mounting :(
D/Vold ( 124): Volume sdcard state changing 3 (Checking) -> 1 (Idle-Unmounted)
D/VoldCmdListener( 124): volume shared /mnt/sdcard ums

Does anyone have any clue on how does VOLD know which partition to mount?

(My device is LG E405 running rooted stock firmware, android 2.3.)