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> 1. boot up knoppix |
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> 2. create a partition: mkdir /work |
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> 3. mount /work to the root partition: mount /dev/sdc /work |
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> 4. cd /work/usr/bin |
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> 5. run dcfldd: ./dcfldd |
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This is fine, provided that |
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1- if the root partition is [part of] what you're copying, you *must* |
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mount it read-only (mount -o ro /dev/sdc /work) |
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2- the dcfldd executable is linked statically. If it uses dynamic |
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linking, your "live" system -- knoppix in this case -- must have exactly |
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the same library versions (especially glibc) as the gentoo system. |
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>> Or is there a way to do such copies from a one disk to another while |
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>> one disk is booted??? |
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The point is not with being "booted" (i.e., part of the running system) |
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or not: you *cannot* reliably perform a sector-by-sector copy of any |
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write-mounted partition without special support either at the FS or |
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block device level (i.e. snapshots). |
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> Sure, but the running disk/sector would have temporary files that would |
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> not consistently hash when you did the hash check. |
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That is only a minor part of the problem. The real issue is that if |
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*anything* writes to the source partition while you are halfway through |
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copy, you risk ending up with inconsistencies in the filesystem |
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metadata. Doing a fsck on the copy will probably fix that, but you risk |
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losing or corrupting data. |
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And no, hashing as described in the previous post will *not* catch any |
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differences in this case, as the "source" hash is computed from what is |
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read during the copy (which, barring hardware problems, is what gets |
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written on the target disk) and not from the whole contents of the |
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source partition after the copy (or at any single point in time). |
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> If you do this, try it in linux without bringing up X. |
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That's definitely not enough: at the very least, boot up in single-user |
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mode and remount all your partitions read-only (mount -o remount,ro). |
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This will break things on a running system (e.g anything that writes to |
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/var and /tmp will throw errors or stop working), but it will allow you |
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to produce consistent partition images. |
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andrea |
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