Baslinux mailing list

[sindi keesan <keesan AT sdf.lonestar.org>]

On Tue, 21 Nov 2006 3aoo-cvfd AT dea.spamcon.org wrote:

> sindi keesan wrote:
> > Several websites suggested specifying a larger block size than the
> > default to speed up copying:
> >
> > dd if=/dev/had of=/dev/hdb bs=8k   - copies in 8k blocks.
>
> If you know the sizes of the HD buffers of the two
> drives, set the bs to the size of the smaller buffer.


I just learned that drives used to have 256K-512K buffers in the late 
nineties (6-13GB) and a 40GB drive or a 250GB drive can have 4MB or 8MB.
850MB or 1.2GB WDC - 64K.     Conner 540MB 64K.

Laptop Toshiba 4GB 0K buffer.

Above using a free Win31 program.

You can use linux instead:

hdparm -tT /dev/hda  (1.2GB WDC)
Timing buffer-cache reads:  128MB in 1.17 seconds=109.40 MB/sec
Timing buffered disk reads:  .... 6.03 MB/sec

hdb (10GB):  113.27 MB/sec   22.07 MB/sec

This gives relative disk speeds.  Is there some free linux diagnostic 
program that gives more detailed access and transfer time info like 
DOS spinrite or syschk?

Info:
hdparm -i /dev/hda   gives 8 lines of drive info
BuffSize=128kB (1.2GB WDC). 
hdb BuffSize=512kB (10GB Seagate)

I looked up online a 340MB Conner - 32k,  a 540MB Conner - 64k
120MB Toshiba or Conner - 32k
bs=32k should be safe

keesan AT sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org