UBIFS: Does ubifs have volumes size min limitation?

[Nancy]

Hi,
    The total size of mtd partitions which will be attached by ubi is 50MiB,
    #ubimkvol -d 0 -n 0 -N ubifs -s 47MiB
   # mount -t ubifs ubi0:ubifs /mnt/1
   UBIFS error (pid 807): validate_sb: bad lsave_cnt
   UBIFS error (pid 807): validate_sb: bad superblock
   mount: mounting ubi0:ubifs on /mnt/1 failed: Invalid argument

   It is OK when the volume size is large.
   Does ubifs have volumes size min limitation? why? and what is it exactly?

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Best wishes,
Nancy