Sponsored Content
Full Discussion: dd bytesize
Top Forums UNIX for Advanced & Expert Users dd bytesize Post 302515137 by programAngel on Tuesday 19th of April 2011 08:00:10 AM
Old 04-19-2011
dd bytesize

I read the manual about the dd and the example and I have seen the use of the bs option, the byte size.

However how can you know that you need to use it and how can you know what size to give it?

like in wwikipedia they give the following:
Quote:
Using dd to duplicate one hard disk partition to another hard disk:
dd if=/dev/sda2 of=/dev/sdb2 bs=4096 conv=noerror
but why 4096 and why mention it at all
 
WREN(3) 						     Library Functions Manual							   WREN(3)

NAME
wren, ata - hard disk interface SYNOPSIS
bind #H[drive] /dev bind #w[target[.lun]] /dev /dev/hd0disk /dev/hd0partition /dev/sd0disk /dev/sd0partition ... DESCRIPTION
The hard disk interfaces (wren, #w, is a SCSI disk; ata, #H, is an IDE or ATA disk) serve a one-level directory giving access to the hard disk partitions. The parameter to attach defines the numerical SCSI target and logical unit number or the IDE drive number to access. Both default to zero. Each partition name is prefixed by hd and the numeric drive identifier. The partition always exists and covers the entire disk. The size of each partition as reported by stat(2) is the number of bytes in the partition, so the size of is the size of the entire disk. The partition also always exists; it is the last block on the disk for SCSI, second to last for IDE. If it contains valid partition data, those partitions will be visible as well. Every time the device is bound, the partitions are updated to reflect any changes in the parti- tion file. The format of the partition file is the string plan9 partitions on a line, followed by partition specifications, one per line, consisting of a name and textual strings for the block start and limit for each partition on the disk. The program prep(8) writes the partition table for the disk; its use is preferred to writing it by hand. SEE ALSO
prep(8), scsi(3) SOURCE
/sys/src/9/port/devwren.c /sys/src/9/pc/devata.c WREN(3)
All times are GMT -4. The time now is 09:07 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy