The AtomicLog + LogDrive: Strong vs weak sealing

This post continues to elaborate on Virtual Consensus and the new Loglet abstractions of the AtomicLog and LogDrive. My last post focused on composability, this post looks at log sealing.A common aspect of segmented logs is that when extending the log with a new segment, the current active segment needs to be sealed to prevent further appends. This post discusses segment sealing in the AtomicLog and LogDrive abstractions.I’m going to treat Virtual Consensus here less as a fixed API and more as a collection of architectural patterns and correctness requirements. The Delos paper defines a specific Loglet API, and the AtomicLog in the LogDrive paper implements that API verbatim. But the implementer has some flexibility regarding where the responsibilities related to seal enforcement live (which is discussed in this post). The single value registerThe LogDrive is an unusually weak abstraction. It is an abstraction over single-value linearizable registers (an address is only required to…