this post was submitted on 23 Feb 2024
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The big advantage of Clonezilla or using dd is you make a perfect 1:1 copy of the disk so you're pretty confident it will restore perfectly, but you need a disk of at least the same size and so on. Also perfect if you're trying to do file recovery and so on, because even corrupted or entirely unreachable data is still technically on the disk.
That's very inefficient when you have say, 5GB used of a 1TB disk, although compression will help a bit. But that's where more specialized tools comes in: what if we could only backup the actual data, and end up with a 5GB backup before compression.
That's useful and nice, but can't possibly deal with corrupted or deleted files since it'll just skip over them. The backup is only as good as all the filesystem features the archiver can encode. On Linux, tar has us pretty well covered as long as you only need relatively standard features like owners, groups. If you zip your root Linux partition you'll end up with broken ownership and permissions, because it doesn't encode ACLs and xattrs and hardlinks and whatever else. On NTFS, since it's proprietary, undocumented and a fairly complex filesystem, it's much riskier. If you backup your game library, you're probably fine, but if you want Windows to boot after a restore, you need a much more complete backup and if you don't want to take risks, whole partition backups are much safer. ntfsclone exists but I just don't trust it like I would trust tar to backup my ext4 partitions correctly.
So it's all a tradeoff. Do you want efficiency, or do you want reliability? How much of the information can you lose? Like, if you backup your C: drive on Windows but only care about your files and documents but not the Windows install itself, then it makes sense to just archive the files rather than a block copy.
So, what do you expect from your backups? The answer to that question also answers this thread.
for a large drive with only partial data you can make dd quicker by reducing partition size. Then fdisk to list byte size of (cylinders x bytes) in header output, and units listed for end of partition. you then use dd with bs=(cyl x bytes) count=(units+1) so dd stops at the last block of partition. once copied you can resize partition. it is how I fit a duplicate of my nas OS img on a 4 gig USB stick img for redeploy. DD is faster and then resize partitions after
You'd probably be better off with dd if=/dev/zero of=file.zero to zero out empty space, dd copy the whole drive, then compress the copy. I wouldn't fuck around with partitions on something I want to back up
For sure, but in my case I didn't want a copressed copy, I wanted a working fully functional drive image
Probably safer to image the whole partition then shrink the image, then. Not sure exactly how I'd go about it, but I'm sure it's not too bad, probably three arcane shell commands
Yes, zero spacing and compress. In my case I was building a direct clone backup for when nas might fail and I can swap drive innediately, but did not want to wait hours to dd the empty drive to an image file.