Re: Is it really necessary to mirror the physical log?

Jacob Salomon wrote: [SNIP] > Q: If I choose not too mirror the dbspace containing the physical log > and that DBspace gets corrupted, is recovery still possible without > going back to archive tapes? Would fast recovery still work, albeit > with the possible loss of some recent updates? > > My suspicion is that mirroring the physical log is a waste of disk space > as well as I/O bandwidth when it gets flushed. Truth be told the result of Logical Recovery without Physical Recovery is the same if all logical log records are available. This is mathematically provable. HOWEVER, having said this, the engine WILL NOT come up if it cannot perform Physical Recovery and while Tech Support can bypass Physical Recovery and force the engine to go online, this will also skip Physical Recovery. Physical Recovery is REQUIRED for Buffered Logging when an entire log file of partial transaction log records may be lost and even for Unbuffered Logging when the log records in the LOGBUF is still at risk during a crash and cannot be rolled back. So, the final answer is YES you need to mirror your Physical Log space.