  Blockchain has attracted a broad range of interests from start-ups,
enterprises and governments to build next generation applications in a
decentralized manner. Similar to cloud platforms, a single blockchain-based
system may need to serve multiple tenants simultaneously. However, design of
multi-tenant blockchain-based systems is challenging to architects in terms of
data and performance isolation, as well as scalability. First, tenants must not
be able to read other tenants' data and tenants with potentially higher
workload should not affect read/write performance of other tenants. Second,
multi-tenant blockchain-based systems usually require both scalability for each
individual tenant and scalability with number of tenants. Therefore, in this
paper, we propose a scalable platform architecture for multi-tenant
blockchain-based systems to ensure data integrity while maintaining data
privacy and performance isolation. In the proposed architecture, each tenant
has an individual permissioned blockchain to maintain their own data and smart
contracts. All tenant chains are anchored into a main chain, in a way that
minimizes cost and load overheads. The proposed architecture has been
implemented in a proof-of-concept prototype with our industry partner, Laava ID
Pty Ltd (Laava). We evaluate our proposal in a three-fold way: fulfilment of
the identified requirements, qualitative comparison with design alternatives,
and quantitative analysis. The evaluation results show that the proposed
architecture can achieve data integrity, performance isolation, data privacy,
configuration flexibility, availability, cost efficiency and scalability.
