Meet Hadoop presentation: the math from page 5

[Stefan Groschupf <sg...@101tec.com>]

Hi,
I tried to better understand slide 5 of "meet hadoop":
http://wiki.apache.org/hadoop-data/attachments/HadoopPresentations/attachments/oscon-part-1.pdf
The slide says is:
given:
–10MB/s transfer
–10ms/seek
–100B/entry (10B entries)
–10kB/page (1B pages)

updating 1% of entries (100M) takes:
–1000 days with random B-Tree updates
–100 days with batched B-Tree updates
–1 day with sort & merge

I wonder how exactly to calculate the 1000 days and 100 days.
time for seeking = 100 000 000 * lg(1 000 000 000) * 10 ms =  
(346.034177 days)
time to read all pages = 100 000 000 * lg(1 000 000 000) * (10kB/10MB/ 
s) =  33.7924001 days
Since we might need to write all pages again we can add another 33  
days, though the result is not a 1000 days, so I do something  
fundamentally wrong. :o

Thanks for any help...

Stefan