Subject: Re: Suggestions on CCD Interleave (also, large-block large-cyl UFS)
To: Alexis Rosen <>
From: Greywolf <>
List: current-users
Date: 01/31/1999 20:53:48
Is any of this useful on non-symmetric disks, i.e, I have differently sized
partitions on differently sized disks.


On 31-Jan-99 Alexis Rosen wrote:
# (Curt Sampson) wrote:
#> Has anyone done any benchmarking work on ccd interleaves to determine
#> which ones are better and worse? I notice that the ccdconfig manual
#> page gives 16 as an example interleave, but I've found that powers
#> of two tend to concentrate inode activity on one drive (I've seen
#> cases where I untar a file and one drive in the ccd is quite active
#> while the other is virtually idle). I've been using 96, (which is
#> about 20% faster than 32 when untarring a large directory tree with
#> a lot of small files in it), but haven't really done a lot of
#> experimentation yet to see if perhaps prime interleaves or something
#> like that would be more optimal.
# I did some benchmarks a couple of years ago to see what would work best
# for a traditional news system (ie, lots of small-file writes and reads).
# To my surprise, really big interleaves were best, at least for reads. And,
# like Curt, I saw that non-power-of-two sizes were a win, though I didn't
# figure out why or pursue that as strongly as I should have.

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