Sysbench OLTP, transactions per second
When dealing with high performance, low latency storage devices, such as SSD cards, one finds bottlenecks in new places. This is a story about such a bottle neck and how to work around it.
One unique feature of InnoDB is the double write buffer. This buffer was implemented to recover from half-written pages. This can happen in case of a power failure while InnoDB is writing a page (16KB = 32 sectors) to disk. On reading that page, InnoDB would be able to discover the corruption from the mismatch of the page checksum. However in order to recover, an intact copy of the page would be needed.
The double write buffer provides such a copy. Whenever InnoDB flushes a page to disk, it is first written to the double write buffer. Only when the buffer is [Read more...]