[dm-crypt] Does luksFormat write the full size of the device?

Charles Cazabon charlesc at pyropus.ca
Sun Jun 26 05:39:01 CEST 2016


I'm currently initializing a fairly large LUKS crypt device, about 33TiB.
I've done this before, but not for quite a while, so I can't remember how long
it normally takes.  My current cryptsetup invocation has been running for
about 24 hours, taking 100% of one CPU core for that entire time.  If there's
I/O happening, iostat isn't showing it.

If `cryptsetup luksFormat` has to write the entire contents of the underlying
block device, then this length of time is reasonable - but I don't recall if
it has to do that.

Is this long runtime normal for initialization of a device of this size?

System is Debian Wheezy with a mainline 4.6.2 kernel, cryptsetup 1.4.3 from
the normal Debian package.


Charles Cazabon                              <charlesc at pyropus.ca>
Software, consulting, and services available at http://pyropus.ca/

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