UBIFS space consumption

[Vikram Narayanan]

On 1/18/2013 10:25 PM, Vikram Narayanan wrote:
> I am using UBIFS with the below partitioning layout.
>
> <6m(bootloader)
> 512k(environment)
> 512k(redundant-environment)
> 5m(kernel),
> 170m(filesystem),
> 40m(user_data1),
> -(user_data2)>
>
> For the UBI volume 0 which has 170 MiB,
> ubinfo reports 164.7 MiB, which is explained by:
>
> (PEB size - LEB size) * (no of PEB's - reserved PEBs)
> (256 - 248) * (680 - 6) = 5.392 MiB
> Total size = 170 MiB - 5.39 = 164.6 MiB
>
>
> root at BOX:/# ubinfo /dev/ubi0
> ubi0
> Volumes count:                           1
> Logical eraseblock size:                 253952 bytes, 248.0 KiB
> Total amount of logical eraseblocks:     680 (172687360 bytes, 164.7 MiB)
> Amount of available logical eraseblocks: 0 (0 bytes)
> Maximum count of volumes                 128
> Count of bad physical eraseblocks:       0
> Count of reserved physical eraseblocks:  6
> Current maximum erase counter value:     5
> Minimum input/output unit size:          4096 bytes
> Character device major/minor:            253:0
> Present volumes:                         0
>
> But according to "df",  UBI volume 0 is sized 148.9 MiB. That's, 15.8
> MiB more in terms of consumption.
>
> root at BOX:/# df -h
> Filesystem                Size      Used Available Use% Mounted on
> ubi0:rootfs             148.9M    132.8M     16.1M  89% /
> root at BOX:/#
>
> Can someone explain where this 15 MiB is getting lost?

Artem, Any ideas on this?

Thanks,
Vikram