Re: WAPL/RAIDframe performance problems

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> 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.

Yes.

> So the position of the superblocks (one exists in each cylinder
> group) is rather irrelevant.

Semi-.  You want your blocks (and frags, if applicable) to be stripe-
and sector-aligned.  However, the superblock is block-aligned, at least
in FFS versions I've worked with, so if it's aligned properly then all
blocks will be too.

> What is more likely to cause grief is 512 byte writes - since modern
> disks have 4k physical sectors.

Indeed.  And some of them lie about it, too. :(

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