[Trilug-ontopic] Device Mapper, LVM, LUKS

Alan Porter porter at trilug.org
Mon Aug 8 13:09:54 EDT 2011

> though I note it says "there are lots of ways
> to very quickly get into trouble! Practice with loop
> devices before jumping into your main HD."

Treat these tools with the same respect that you might
treat "dd". For example, it's pretty cool to save your MBR
using "dd if=/dev/sda of=mbr.img bs=444 count=1". [1]
But you really want to be sure before doing the copy in the
reverse direction, because you can really hose your partitions
very quickly.

So as long as you are cautious before doing things like
"pvremove /dev/sda2", you should be OK. Likewise, be
careful about creating volume groups that span removable
disks, like USB drives. If the machine comes up and can only
find half of the physical volumes that it needs for a particular
volume group, you can end up in a very awkward position.

[1] If you're curious about why I said "444" instead of "512",
the partition table starts 444 bytes into the first block. Before
that is all bootloader code.

# ɹǝʇɹoԀ uɐl∀

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