Date: Tue, 13 Jul 1999 14:50:34 +0200 (CEST) From: Luigi Rizzo <luigi@iet.unipi.it> To: hackers@freebsd.org Subject: Why 'dd' does not seek over 'char' devs (specifically raw disk partitions). Message-ID: <199907131250.OAA00397@prova.iet.unipi.it>
next in thread | raw e-mail | index | archive | help
Hi, i have a question. Why 'dd' does not seek over 'char' devs (specifically raw disk partitions). My point is, when a disk develops problems, sometimes it is possible to recover nearby sectors e.g. using dd, and seeking to the right block. However running dd over the char device (rwd*) takes forever because the seek on char devices is implemented by reading instead. Using the cooked device is problematic because the buffering causes multiple sectors to be read and this may cause errors if some block nearby has problems. I notice that on output lseek _is_ used also on char devices. Ideas ? cheers luigi To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199907131250.OAA00397>