ARIES

1
ARIES

• What is ARIES?
• A Transaction Recovery Method Supporting
  Fine-Granularity Locking and Partial Rollbacks
  Using Write-Ahead Logging.

2
Two Principles

• First, in ARIES, changes always take the system
  forward.

3
Two Principles

• In ARIES,
• A single LSN is used on each page to track the
  pages state.
• LSN is placed in the page_LSN field of the
  updated page.

4
Two Principles

• Second, during recovery, history is repeated.
• 1, ARIES replays the Log to bring the system
  back to the point of crash.
• 2, undo failed transactions

5
Two Principles

• Avoid application of log records unnecessarily.
• e.g. using UndoNxtLSN to track undo proecsses.

6
Three Passes

• In ARIES, there are three passes during
  recovery.
• Analysis pass
• Redo pass
• Undo pass

7

8
CheckPoints

• Switch to a new log file if possible.
• Freeze the log (for the transition to a new log
  file)
• Flush current log file
• Create and flush the new log file (with file
  number 1 higher than the previous log file). The
  new log file becomes the current log file.
• Unfreeze the log
• Start checkpoint transaction
• Gather interesting information about the
  rawStore
• The current log instant (redoLWM)
• The earliest active transaction begin tran log
  record instant (undoLWM) , all the truncation LWM
  set by clients of raw store (replication)
• Clean the buffer cache
• Log the next checkpoint log record, which
  contains (repPoint, undoLWM, redoLWM) and commit
  checkpoint transaction.
• Synchronously write the control file containing
  the next checkpoint log record log instant
• The new checkpoint becomes the current
  checkpoint. Somewhere near the beginning of each
  log file should be a checkpoint log record (not
  guarenteed to be there)
• See if the log can be truncated

9
CheckPoints

• What is the difference between Derby and ARIES?
• ARIES does not require that dirty pages be
  flushed to disk. (Derby does)