Hi Oleg, On Sun, Dec 30, 2012 at 10:40:31AM +0200, Oleg Goldshmidt wrote: > On Sun, Dec 30, 2012 at 8:46 AM, shimi <[email protected]> wrote: > > I really don't think so. SSDs (IMHO) makes computer much faster due to the > > VERY low seek time - the time it takes you to get a block. Compare 10-20ms > > with ~0.1ms. A regular hard drive simply wastes a lost of time seeking the > > data, instead of... reading it :) > > Absolutely correct. However, there is a tiny fraction of the seek time > that is not always a waste, and I think it is worth mentioning. There > is, I believe, a consideration that is usually overlooked when SSDs > are considered for server use, including a "desktop" that is used as a > server, which is why I am mentioning it here. In a server, magnetic > disk rotation - or, rather the air turbulence generated between the > rotating disk and its enclosure - is the only source of entropy that > makes random numbers random (seek times have a tiny random component > due to the turbulence, and it is captured). This does not apply to > SSDs, and as a result your security may be compromised (attacks > exploiting not very random RNGs are well known).
Recent Intel CPUs introduced the RDRAND instruction that is essentially a Random Number Generator. Recent kernels (v3.2 and later) added support for this instruction. See http://git.kernel.org/linus/628c6246d4. See also the related commit (from v3.6) at http://git.kernel.org/linus/c2557a303 (and note the funny commit log). These patches were backported to all supported stable kernel trees (back to v2.6.32). > In a laptop or a desktop entropy is also generated by keyboard and > mouse (which may or may not be good enough). In a server that hardly > applies. baruch -- http://baruch.siach.name/blog/ ~. .~ Tk Open Systems =}------------------------------------------------ooO--U--Ooo------------{= - [email protected] - tel: +972.2.679.5364, http://www.tkos.co.il - _______________________________________________ Linux-il mailing list [email protected] http://mailman.cs.huji.ac.il/mailman/listinfo/linux-il
