On Sun, 10 Jan 2010, Henrik Johansson wrote:
As an interesting aside, on my Solaris 10U8 system (plus a zfs IDR), dd
(Solaris or GNU) does
not produce the expected file size when using /dev/urandom as input:
Do you feel this is related to the filesystem, is there any difference between
putting the data in a file on
ZFS or just throwing it away?
My guess is that is due to the implementation of /dev/urandom. It
seems to be blocked-up at 1024 bytes and 'dd' is just using that block
size. It is interesting that OpenSolaris is different, and this seems
like a bug in Solaris 10. It seems like a new bug to me.
The /dev/random and /dev/urandom devices are rather special since
reading from them consumes a precious resource -- entropy. Entropy is
created based on other activities of the system, which are expected to
be random. Using up all the available entropy could dramatically
slow-down software which uses /dev/random, such as ssh or ssl. The
/dev/random device will completely block when the system runs out of
entropy.
Bob
--
Bob Friesenhahn
bfrie...@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
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