[Ocfs2-tools-devel] some questions for mkfs.ocfs2 18/5

[Coly Li]

Hi,

These days, when I read code of mkfs.ocfs2, there are some questions (just
beginning) which I can not understand. I post the questions here, wish someone
can help me.

- is 2MB for heart beat device is enough ?
  from mkfs.ocfs2/mkfs.c line 1266, as bellow
      if ((ret * blocksize) > (2 * 1024 * 1024)) {
  is seems 2MB size of heart beat device is enough. I don't know how this number
is from. And for large number of nodes in cluster, e.g. 128 nodes, is the size
still enough ?

- what is specified_size_in_blocks for ?
  Is it the size (in blocks) specified by parameters to mkfs.ocfs2, which can
overwrite the default volume size in blocks ?

- why writes 1MB to both head and end of a volume ?
  I can understand writing the CLEAR_CHUNK bytes to volume head. Is there
anything valuable to be escaped in the end of the volume ?

Thanks in advance for your feedback :)

-- 
Coly Li
SuSE Labs