Truths and Lies about DB_LOST_WRITE_PROTECT

David Loinaz

The name of this parameter always makes me think that if it is set, the system will be protected against lost writes, so it will prevent occurring.

A data block lost write occurs when an I/O subsystem acknowledges the completion of the block write, while in fact the write did not occur in the persistent storage, but knowing that I/O subsystem is not part of the Oracle Database code, you may  wonder, “how Oracle is able to protect against a lost write when it is not responsible for writing“. Well, in my opinion, the name of this parameter is misguided, because it is not preventing lost writes.

So why use it? When you have a lost write situation, the sooner you detect it, the better, and this parameter is very useful to detect lost write as soon as possible and will help you to, under some circumstances, be…

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