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Re: 512e vs 4K sector confusion

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Hi andy,

Am 14.01.2024 um 09:15 schrieb Andy Smith:
> On Sun, Jan 14, 2024 at 08:01:52AM +0000, Andy Smith wrote:
>> If necessary and if there is a way, I *can* nuke off the target
>> machine's "foo" volume group and recreate the RAID array if I have
>> to make it 512e format. But obviously I'd like some way to move this
>> disk image and have it still work without having to meddle inside it
>> much — it is a VM disk.
> 
> I think I may be able to use hdparm to reformat these Ultrastar DCs
> from 4kn to 512e…
...
> Thoughts?


Reshaping the target system's storage may be the quickest and most 
reliable solution.

If you expect there may be future cases with similar problems -- the 
other way around would be much worse, i.e. you have a source storage 
with 4k sectors, and target that does not support it -- these posts

https://unix.stackexchange.com/questions/748208/lvm-and-device-mapper-logical-volume-device-sector-size

https://unix.stackexchange.com/questions/676534/creating-an-ssd-partition-with-a-different-block-size

might be good starting points to work out a real solution.

As far as I know, however, it is not possible to change the block sizes 
using any of the software layers involved -- they all inherit from their 
base layer, which means from the actual devices, eventually.

Fortunately, I never had to solve such issues myself, but that's 
probably because I prefer working at the file system level. Block level 
just has too many pitfalls for my simple tastes ;-)

I'm getting curious to see what happens if I have to mix 512- and 
4k-sector disks in one RAID, though.

Cheers,

Arno


-- 
Arno Lehmann

IT-Service Lehmann
Sandstr. 6, 49080 Osnabrück

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Thread

512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-14 09:10 +0100
  Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-14 09:20 +0100
    Re: 512e vs 4K sector confusion "Alexander V. Makartsev" <avbetev@gmail.com> - 2024-01-14 12:30 +0100
    Re: 512e vs 4K sector confusion Arno Lehmann <al@its-lehmann.de> - 2024-01-14 12:40 +0100
  Re: 512e vs 4K sector confusion "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-14 14:30 +0100
    Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-14 17:20 +0100
      Re: 512e vs 4K sector confusion "Thomas Schmitt" <scdbackup@gmx.net> - 2024-01-14 18:00 +0100
  Re: 512e vs 4K sector confusion Timothy M Butterworth <timothy.m.butterworth@gmail.com> - 2024-01-14 19:20 +0100
  Re: 512e vs 4K sector confusion Stefan Monnier <monnier@iro.umontreal.ca> - 2024-01-15 05:40 +0100
    Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-15 06:40 +0100
      Re: 512e vs 4K sector confusion Nicolas George <george@nsup.org> - 2024-01-15 22:30 +0100
      Re: 512e vs 4K sector confusion Nicholas Geovanis <nickgeovanis@gmail.com> - 2024-01-15 22:30 +0100
        Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-16 01:40 +0100
        Re: 512e vs 4K sector confusion Teemu Likonen <tlikonen@iki.fi> - 2024-01-16 17:40 +0100
      Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-17 08:30 +0100
  Re: 512e vs 4K sector confusion Andy Smith <andy@strugglers.net> - 2024-01-20 22:30 +0100

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