[TriLUG] OT: hd speed with 33MHz and 100MHz controller are the same

[Jim Ray]

How can the bus be the bottleneck when the reciprocal of the bus frequency
is an order of magnitude faster than the hard disk access time?

Regards,
 
Jim
 
Jim Ray, President
Neuse River Networks
tel: 919-838-1672 cell: 919-606-1772
http://www.Neuse.Net
 
Connecting You to the World since 1997
 
> -----Original Message-----
> From: trilug-bounces at trilug.org [mailto:trilug-bounces at trilug.org] On
Behalf Of Joseph
> Mack NA3T
> Sent: Wednesday, June 13, 2007 8:25 AM
> To: Triangle Linux Users Group discussion list
> Subject: Re: [TriLUG] OT: hd speed with 33MHz and 100MHz controller are
the same
> 
> On Tue, 12 Jun 2007, Robert Dale wrote:
> 
> > The bus probably is 33MHz, 66MHz at most.  And it probably is the
bottleneck.
> > Just as you wouldn't expect to Gb speeds on a 10baseT network just
> > because you plug in a GigE card.
> 
> I hadn't realised there was as much happening between the
> CPU and the disk. Since badblocks is writing the same data
> over and over, I would have thought it would all be cached.
> 
> It's taken overnight to write the first 0xaaaaaaaa bits to
> the disk. It's just started to read them back. It will be 4
> days before its finished my new 320G disk at 33MHz.
> 
> > A better benchmark would be to use something like bonnie++ [1] on each
> > disk separately and compare numbers.  It measures raw throughput
> > through various tests - it does not try to verify data like badblocks
> > (which potentially could be cpu bound).  You can also limit the size
> > of files.
> 
> will give it a go in 4 days ;-) thanks
> 
> Joe
> 
> --
> Joseph Mack NA3T EME(B,D), FM05lw North Carolina
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