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Table 1: Positions and feasibility of performance isolation.
Tenant
Affinity
Session
Stickiness
Pos. 1 Pos. 2 Pos. 3
affine
no no yes yes
yes no yes yes
non
no yes yes yes
yes no yes no
cluster
no no yes yes
yes no yes no
as the overall amount of requests is required in order
to guarantee performance isolation. It was explained
why, in many scenarios, performance isolation is not
possible without information about the request distri-
bution (Position 1), or directly in front of the appli-
cation instance (Position 3). Offering a superset of
the information available at the two other positions,
Position 2 is the only one that allows to realize per-
formance isolation for all affinity combinations.
5 CONCLUSIONS
It was shown that performance isolation between ten-
ants is an important aspect in multi-tenant systems,
and that serving a huge amount of tenants requires
the existence of several application instances and a
load balancer that distributes requests among them.
While existing work focuses on concrete algorithms
and techniques to enforce performance isolation, this
paper focuses on a conceptual realization of perfor-
mance isolation in a load-balanced multi-tenant sys-
tem.
We were able to outline that, from an information-
centric point of view, the best placement strategy for
a performance isolation component that leverages re-
quest admission control is directly after the load bal-
ancer. At this position, information about the allo-
cation of requests to processing nodes as well as the
overall amount of requests from a tenant is given. It
was shown that the positions before the load balancer,
or directly before the applications have disadvantages
which make it impossible to realize performance iso-
lation in every scenario. However, the use of fine-
grained information about a processing node’s state
may increase the quality of performance isolation and
this is best possible when the component is placed at
the respective processing node. Consequently, data
has to be transmitted via the network in the other
cases, which leads to a trade-off decision depending
on the concrete scenario.
Our future research focuses on providing a com-
plete architecture to enforce and evaluate perfor-
mance isolation based on the here presented results.
ACKNOWLEDGEMENTS
The research leading to these results has re-
ceived funding from the European Union’s Seventh
Framework Programme (FP7/2007-2013) under grant
agreement N
o
258862.
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