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Re: WAPL/RAIDframe performance problems

> For example, /usr/include/ufs/ffs/fs.h suggests that the
> super block could bein one of 4 different places on your partition,
> depending on what size your disk is, and what version of superblock you're
> using. 

From my memory of the ffs disk layout, fs block/sector numbers start from
the beginning of the partition and just avoid allocating the area
containing the subperblock copies.
So the position of the superblocks (one exists in each cylinder group)
is rather irrelevant.

What is more likely to cause grief is 512 byte writes - since modern
disks have 4k physical sectors.
I think netbsd tends to do single sector writes for directory entries
and the journal - these will be somewhat suboptimal!


David Laight:

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