Jan Engelhardt wrote: [...]
BLKRRPART can be issued with `blockdev --rereadpt`. You do not need to wipe a disk fully and repeatedly just for that ioctl.
But the point is: if /dev/sda3 is currently mounted as per my howto, reloading /dev/sda after adjusting the table will return EBUSY. Hence the reboot. (Else you'd have to switch to a magic tmpfs.. all complicated and not worth pursuing time-wise.) [...]
Good to know. The only thing I have used dd in the past several years has been as a storage IO generator without having to install anything. I had recently read an article about conv=sync,noerror being used when working with raw disk devices so the ddrescue alternative is valuable knowledge.
Well this is exactly the argument _for_ using ddrescue: not having to figure out bs=, skip= and seek= crap under pressure, and actually getting a time estimate on how long the operation will take (at least for larger transfers).
Sounds like a great tool, and I will give it a try next time I need a dd equivalent and pass along the info, since I suspect not too many sysadmins are aware it exists. To that point, the only results Google finds on suse.com are from HW 20 and Packagehub, for example, while this KB is an obvious case where ddrescue would probably be preferable https://www.suse.com/support/kb/doc/?id=000018742 Since as a sysadmin, it's an expectation to follow instructions provided by a vendor, it's hard to see ddrescue having much general adoption when official documentation exclusively specifies dd.
Why prevent? Switching filesystem does not happen automatically, you have to really work towards it.
I had considered swapping the root disk with one from a template with XFS and applying any changes to /etc and /var that might be needed by hand because I have seen that work before. This rsync/mkinitrd method using another partition on the same disk looks much cleaner, more straightforward and repeatable. I just wasn't sure if there had been any recent changes to these steps that may have been required since downstream's 2014 GA release and it will take a fair amount of effort to get everything put in place to lab it out.