mkfs and 80SC interleaving

[Charles Anderson]

>From article <42900002 at m.cs.uiuc.edu>, by coolidge at m.cs.uiuc.edu:
> Does anyone know the "right" interleaving numbers for an internal (or,
> for that matter, an external) 80SC, especially one used mostly as
> an NFS-mounted server drive?

>From the 1.1 man page for mkfs:

             Note: The proper selection of the m and n
             parameters can improve disk efficiency.  Disks which
             have full or partial track buffering should specify an
             m and n of 1 and 1; m and n for other disks must be
             determined by trial and error, as the disk latency is
             related to rotational latency and to the speed of the
             central processing unit.

As the Q-280 (alias 80SC) has a "dual port 14K-byte FIFO data buffer"
(from the Q200 series OEM manual), it should be obvious to the casual
observer :-) that the m and n values should be 1 and 1.  I've tried
this and it really does work.  (the difference between 40K/sec and
140K/sec read throughput under 1.1)  It should also be noted that this
option is also available in fsck (-s1:1).  This re-orders the free list
to use the parameters specified.  I have observed that the free list
degrades with normal use and that "fsck -s" restores so it runs like
new.

-- 

Charles.
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