Date: Fri, 12 Jun 2020 21:41:34 -0700 From: David Christensen <dpchrist@holgerdanske.com> To: freebsd-questions@freebsd.org Subject: Re: Makin' backups -- questions Message-ID: <52e039ec-7ec1-d523-e64b-d76a069dde9b@holgerdanske.com> In-Reply-To: <94012.1592006407@segfault.tristatelogic.com> References: <94012.1592006407@segfault.tristatelogic.com>
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On 2020-06-12 17:00, Ronald F. Guilmette wrote: > But seriously, I have found that copying whole partitions is often easiest > using the Linux gparted tool. I use LUKS, GELI, and ZFS. Unfortunately, I do not believe gparted nor Clonezilla support them: https://gparted.org/ https://www.clonezilla.org/ > DD is quite obviously an -extremely- low > level tool, and rather ham-fisted. Clonezilla can also copy individual > partitions. Me personally? I wouldn't use DD except to copy -everything- > between two drives having exactly the same number of sectors. I have an assortment of "16 GB" devices of varying sizes: 2020-06-12 20:58:04 dpchrist@tinkywinky ~/hardware $ cat `find samsung sandisk/ultra-fit -name fdisk.out` | egrep '14.. GiB' | perl -pe 's/.+ (\d+ sectors)/$1/' | sort | uniq 30031872 sectors 30375936 sectors 31266816 sectors 31277232 sectors When installing, I use 1 MiB + 14 GiB = 29362176 sectors and leave the rest as unused space. When imaging, I copy from sector 0 to the end of the last MBR partition (FreeBSD slice). I can put the image onto any of the above devices, and the device will boot and work as a system drive. > Note that > if you use DD to copy from a smaller drive to a bigger drive, then afterwards > the BIOS and everything else will tell you that the destination drive's > physical size is -smaller- than it actually is, i.e. exactly equal to the > size of the (smaller) source drive. I haven't seen that. I gather drive metadata and check it into CVS whenever I wipe a device, do a fresh install, take an image, or restore an image. I will pay more attention to 'cvs diff' in the future. I would be curious to see a demonstration console session. > Yet another reason not to use DD to copy either whole disks or partitions... > unless the size of the destination is -exactly- equal to that of the source. I agree that partition sizes must be identical for dd(1) to produce a correct result. But, I know that device sizes do not need to be identical if you use MBR partitioning and leave free space at the end. David
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