Date: Wed, 24 Aug 2005 15:27:28 -0500 From: David Kelly <dkelly@hiwaay.net> To: "Gary W. Swearingen" <garys@opusnet.com> Cc: questions@freebsd.org Subject: Re: creating filesystem images Message-ID: <20050824202728.GA64885@Grumpy.DynDNS.org> In-Reply-To: <n7mzn7dy79.zn7@mail.opusnet.com> References: <430C568B.5060501@azimainc.com> <44d5o3tm57.fsf@be-well.ilk.org> <20050824154854.GA63910@Grumpy.DynDNS.org> <n7mzn7dy79.zn7@mail.opusnet.com>
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On Wed, Aug 24, 2005 at 10:47:06AM -0700, Gary W. Swearingen wrote: > David Kelly <dkelly@hiwaay.net> writes: > > > The advantage of dump/restore is that only the necessary data is > > written. With dd all the unused blocks on the media are also written, > > including the filesystem, which will probably work on the larger card. > > If you don't mind educating me further for no particular need... > > I've long known about the UNIX concept of everything being a string of > bytes, but came to the conclusion early in my Linux days that disks > couldn't be used as a filesystem after a "dd" unless their cylinders > were the same size (or maybe it was just tracks). Has this all gone > away with FreeBSD's removal of "block devices" and/or with LBA disks? When I last did any significant amount of FreeBSD-on-CF, FreeBSD was at 4.6 and I think the CF card hooked in on the SCSI drivers. In any case, back then I had no problems block copying a 32MB CF onto a 256MB CF, boot blocks, partition table, and everything so long as one didn't mind losing everything over 32MB. What I did have problems with is a few 256MB CF's in a lot which were externally identical to the others but a handful of blocks shorter. Thats when I nuked the dd procedure I had inherited and replaced with a script which started with newfs. Newfs was smart enough to detect the size and do the right thing. Yes, tar and/or pax are not able to copy/restore the special BSD flags which dump/restore does. I think I used mtree to beat my final CF image into the desired shape, permissions, owner/group, and BSD flags. -- David Kelly N4HHE, dkelly@HiWAAY.net ======================================================================== Whom computers would destroy, they must first drive mad.
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