Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!pasteur!ucbvax!mtxinu!taniwha!paul
From: paul@taniwha.UUCP (Paul Campbell)
Newsgroups: comp.unix.aux
Subject: Re: mkfs and 80SC interleaving
Message-ID: <362@taniwha.UUCP>
Date: 17 May 89 17:03:31 GMT
References: <42900002@m.cs.uiuc.edu> <30891@apple.Apple.COM>
Reply-To: paul@taniwha.UUCP (Paul Campbell)
Organization: Taniwha Systems Design, Oakland
Lines: 36

In article <30891@apple.Apple.COM> dwells@Apple.COM (Dave Wells) writes:
>In article <42900002@m.cs.uiuc.edu> coolidge@m.cs.uiuc.edu writes:
>>
>>seems to be doing far too much seeking. I suspect that by using the m
>>and n (interleaving) parameters with mkfs the performance could be
>>greatly improved.
>>
>o What interleave was it formatted with.  Did you originally initialize
>  it with HD SC Setup on a Plus or SE?  That'd hurt (not much, but some).

actually this is important if you use mkfs for 1k blocks (rather than mkfs1b
for 512 byte blocks) because you have to always wait for the latency

>o When you used mkfs to create your file systems, did you allow it to
>  use the defaults?  If so that'd hurt lots.  As is documented, the
>  defaults are 7 for the gap and 400 for the "modulo operator."  A gap
>  of 1, 2 or 3 will produce very similar results while 7 is like
>  pouring molasses into the drive.  After talking to bunches of people

yes and one way to fix an existing drive is simply to 'fsck -S' to
rebuild the free list so that future files get laid down in the
right places (it's a good idea to do this every few weeks on any System V
anyway).

Also do you have multiple active partitions on the same disk? the
heads could be bouncing backwards and forwards between them

	hope this helps

	Paul

-- 
Paul Campbell
Taniwha Systems Design			UUCP:		..!mtxinu!taniwha!paul 
Oakland CA				AppleLink:	D3213
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