Re: [ANNOUNCE] cryptsetup 2.2.0-rc1 (experimental)

On Monday, June 17, 2019 10:19 AM, Ondrej Kozina <[email protected]> wrote:

> On 6/15/19 2:49 PM, Jordan Glover wrote:
>
> > One question: does reencryption allows changing block size?
> > For example: old size:512, new size:4096
>
> Hi,
>
> new reencryption code indeed supports change of encryption block size
> (both ways), even in online mode. But user has to ask for it explicitly
> by specifying --sector-size parameter when initializing device
> reencryption. By default we retain original encryption sector size (from
> luksFormat action).
>
> But I strongly recommend to be careful with it. Changing encryption
> sector size on devices underneath existing filesystem is tricky. See my
> post on pvmove of existing fs from dm-crypt with 512 sector size to
> dm-crypt with 4K sector size:
> https://www.saout.de/pipermail/dm-crypt/2019-February/006078.html
>
> You have to ensure the filesystem can handle device limits increase to
> 4K (that's what encryption sector size increase actually does). It's
> safe for fs formatted with blocksize set to 4K. But if fs was formatted
> with blocksize < 4K do not try do not try to increase encryption sector
> size beyond filesystem block size.
>
> Kind regards
> O.

Great, thx for the answer.

Jordan
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