62
seCurity and PrivaCy in smart Grids
threshold SLA levels. However, when the application is allocated suf-
ficient computing resources so that the response time of the requests
is R
avg
, the application is said to be operating at standard SLA levels.
A data center acts as a host to many different applications with vary-
ing input/ output (I/ O), central processing unit (CPU), and memory
characteristics. In addition, each of these applications has a varying
degree of tenacity to operate at threshold SLA levels during differ-
ent times of the day. us, at time t
1
an application i
1
can operate at
threshold SLA levels only for duration τ
i
1
. At time t
2
, the application
can operate at threshold SLA levels for duration τ
i
2
, τ
i
2
≠
τ
i
1
. Again, at
time t
2