  Cloud availability is a major performance parameter for cloud platforms, but
there are very few measurements on commercial platforms, and most of them rely
on outage reports as appeared on specialized sites, providers' dashboards, or
the general press. A paper recently presented at the PAM 2014 conference by Hu
et alii reports the results of a measurement campaign. In this note, the
results of that paper are summarized, highlighting sources of inaccuracy and
some possible improvements. In particular, the use of a low probing frequency
could lead to non detection of short outages, as well as to an inaccurate
estimation of the outage duration statistics. Overcoming this lack of accuracy
is relevant to properly assess SLA violations and establish the basis for
insurance claims.
