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Path: utzoo!linus!philabs!polaris!herbie
From: herbie@polaris.UUCP (Herb Chong)
Newsgroups: net.followup
Subject: Re: Unix from a snob's point of view!
Message-ID: <314@polaris.UUCP>
Date: Mon, 2-Dec-85 15:49:14 EST
Article-I.D.: polaris.314
Posted: Mon Dec  2 15:49:14 1985
Date-Received: Sat, 7-Dec-85 13:28:46 EST
References: <298@weitek.UUCP> <228@polaris.UUCP> <942@wcom.UUCP>
Reply-To: herbie@polaris.UUCP (Herb Chong)
Organization: IBM TJ Watson RC
Lines: 29
Summary: 

In article <942@wcom.UUCP> frodo@wcom.UUCP (James Scardelis) writes:
>> it's partly a function of hardware as well.  tradition has it that all disk
>> blocks are 512 bytes.  this is fine on a smaller machine where there was
>> only 64K to work with, the CPU and memory are slow, and so was the disk.
>> you can make block sizes bigger, but still you have to live with hardware
>> that doesn't understand it.  
>
>	On System V, the physical block sizes are 1K.

as others have pointed out, my understanding of the VAX hardware is that the
physical blocks for paging and stuff like that are 512 bytes.  you can define
larger LOGICAL blocks, but you still end up working with them as collections
of units of 512 bytes.  having larger logical blocks alone can improve system
performance since you can make a bunch of I/O requests in a row.  i don't know
if disk controllers typically used with VAX hardware understand chained
I/O commands as i know IBM 370 channels do.
 

Herb Chong...

I'm still user-friendly -- I don't byte, I nybble....

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