Do we need to flush the log for <START, T> before doing any writing/flushing for it to be recoverable?

For example:

<START, T>

Flush(log)         ====> Is this flush necessary for this to be recoverable?

Write(X, vx')

<UPDATE, T, X, vx>

Flush(log)         ====> Or can we remove the flush above and just flush the <START, T> here?

Flush(X)

<COMMIT, T>

Flush(log)

Commit