From the following information calculate the stripe unit and width:

meta-data=/dev/sda4              isize=256    agcount=16, agsize=923264 blks
         =                       sectsz=512   attr=0
data     =                       bsize=2048   blocks=14771760, imaxpct=25
         =                       sunit=128    swidth=256 blks, unwritten=1
naming   =version 2              bsize=4096
log      =internal log           bsize=2048   blocks=7296, version=1
         =                       sectsz=512   sunit=0 blks
realtime =none                   extsz=65536  blocks=0, rtextents=0

What would be the conseqence of not aligning a filesystem on a stripe unit correctly?

What are the advantages of an external log?

Why would having very few or very many allocation groups be a bad idea?