On Tue, Jun 19, 2001 at 12:49:01PM -0700, [EMAIL PROTECTED] wrote:
> dd lets you define what "block" means for the purpose of accessing the
> input file or the output file with the read or write calls. This may
> apply if the device driver is picky about the record sizes you read or
> write, but may vary from one device/driver to another, or the driver may
> be completely flexible on this value. dd doesn't know what a cluster is,
> but by manipulating its idea of what a block is you may be able to extract
> better performance out of a device driver. For example, when copying a
> floppy disk to an image file, selecting a relatively large number of bytes
> for ibs will let the floppy driver buffering grab as much data as possible
> in each system call (ibs or bs = 32768 for example).
It is often recommended to specify bs=18k when duplicating floppy disks
images, since this block size aledgedly meshes well with the hardware buffer
size of the floppy drive, leading to a faster copy :-).
--
Henry House
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