[dm-crypt] SSD dm-crypt partition alignment

Christoph Anton Mitterer christoph.anton.mitterer at physik.uni-muenchen.de
Wed Aug 25 19:25:58 CEST 2010

On Wed, 2010-08-25 at 18:21 +0200, Milan Broz wrote:
> - cryptsetup 1.1.3 understand topology info provided by kernel,
> if storage (SSD) announces proper values, it is properly aligned
> (kernel with topology ioctl support required)
That was with > 2.6.34, right?

> - devel version (next cryptsetup, change in svn already) will use default alignment
> to 1MiB (if 1 MiB is multiple of topology alignment, it remains 1MiB; otherwise
> it is aligned according to topology info - useful for nonstandard RAID devices)
btw: Is there a rough expectation on when you'll release the next version?

> Aligning to 1MiB is now trend in storage technology and it is safe default
> for most of these configs (I'll describe reasons in release notes).
You've also did that for lvm, right?

> All basic storage tools should now align to optimal values by default
> (like fdisk/lvm2/cryptsetup/mdadm etc) - in recent versions.
> So the whole storage stack should not suffer from possible misalignment.
Do you perhaps know, about the status of cfdisk and gpart?
I personally use fdisk, but those two are also commonly used,... and if
we put that in the FAQ perhaps, it might be worth to add which tools are
known to support it.

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