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From: Milan Broz <mbroz@redhat.com>
To: Peter Smith <peter.smith3882100@gmail.com>
Cc: dm-crypt@saout.de
Subject: Re: [dm-crypt] cryptsetup align problem
Date: Thu, 26 Aug 2010 00:58:00 +0200	[thread overview]
Message-ID: <4C759FF8.5060100@redhat.com> (raw)
In-Reply-To: <AANLkTing13-W-R0rKXQrEZ4a5cKrbjx=HtzFfGpNtsmu@mail.gmail.com>


On 08/25/2010 11:50 PM, Peter Smith wrote:
> I am trying to align a LUKS volume to 512K boundary. I calculate the
> --align-payload value like this:
> 
> (512*1024) / 512 = 1024
> 
> cryptsetup luksFormat --align-payload=1024 /dev/sda1
> 
> When i confirm the task with cryptsetup luksDump /dev/sda2 the Payload
> offset is set to 2048 which is 1024K?
> 
> What am i doing wrong?

Nothing, it works as expected. It is not fixed offset but req. alignment.

Using --align-payload=1024 means alignment to the nearest 512KiB boundary,
because the keyslots space requires more than 512KiB it aligns to next multiple
of it - i.e. 2048 sectors.

If you increase key size (thus keyslots size), it will probably switch to to 3072 etc.

Milan

  reply	other threads:[~2010-08-25 22:58 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-25 21:50 [dm-crypt] cryptsetup align problem Peter Smith
2010-08-25 22:58 ` Milan Broz [this message]
2010-08-26 12:43   ` Peter Smith
2010-09-03 17:58     ` Christoph Anton Mitterer
2010-09-04  9:31       ` Peter Smith
2010-09-05 10:07         ` Milan Broz
2010-09-05 15:07           ` Peter Smith

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