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Points to consider while upgrading Hyperledger Sawtooth

This is applicable to upgrade from version 1.0.X to 1.1.X

  1. Persist the block store, transaction receipt and global state (lmdb files default stored in /var/lib/sawtooth directory).
  2. Persist the keys generated for the validator (default stored in /etc/sawtooth directory).
  3. Hyperledger Sawtooth 1.1.X versions have a major feature introduced where different consensus engine can be plugged into the validator.
    • Validator shall open the listener port so that the consensus engine can be registered to it. This in addition to other ports which are open to transaction processor/event listeners/clients, validator connections. For example, command line option to listen on localhost is as follows
sawtooth-validator --bind consensus:tcp://localhost:5050
  1. When a validator service is restarted, you need to re-register the transaction processor, consensus engine or other components such as event listeners. This is true for all the components which initiates a connection to the validator service, except for the case of validator itself initiates a connection.
  2. Submitted transactions are stored in memory, these are lost when the service is brought down or a new service is brought up.
  3. Client should have a retry mechanism for all the transactions until they are either considered in a block or rejected by the validator.

Note: The validator service would be unavailable for the time period when the upgrade happens. Client can consider this as validator service unavailable and retry the transactions when the validator service is up again.

Transaction Processor upgrades

  • Maintain old versions of transaction processors, even though clients are not sending transactions to the old version. This is required so that when a new validator is added to the network and it needs to catch up with earlier published blocks.

Consensus engine upgrades

  • Maintain older version of consensus engines for a newly added node in the network, to catch up with the earlier blocks.

General practice for deploying a Hyperledger Sawtooth application

  • Transactions may be rejected by a validator if the input rate is higher than what a validator can handle in its queue. The queue maintained by the validator does not have a fixed size, rather the size depends on the rate at which blocks are published. Client should consider this queue full case at validator end and retry the same transaction when the validator is able to handle.

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