FFS - Still using rotational delay with modern disks?

Greg 'groggy' Lehey grog at FreeBSD.org
Mon Dec 17 23:24:02 UTC 2012


On Monday, 17 December 2012 at 16:44:11 -0500, Dieter BSD wrote:
> The newfs man page says:
>
>  -a maxcontig
>  Specify the maximum number of contiguous blocks that will be laid
>  out before forcing a rotational delay.  The default value is 16.
>  See tunefs(8) for more details on how to set this option.
>
> Is this still a good idea with modern drives where the number of
> sectors per track varies, and no one but the manufacturer knows how
> many sectors a particular track has?

No.

It looks as if this, and also a number of comments in sys/ufs/ffs/fs.h
and sys/ufs/ffs/ffs_alloc.c, are leftovers from the Olden Days.  The
value isn't used anywhere that I can see.  Unless somebody can show
that I'm wrong, I'd suggest that this is a documentation issue that I
can take a look at.

Greg
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