On Wed, 19 Aug 2015, Jatin Davey wrote: > On 8/19/2015 1:54 PM, John Hodrien wrote: >> On Wed, 19 Aug 2015, Jatin Davey wrote: >>> We use CentOS 6.6 for our application. I have profiled the application and >>> find that we have a heavy requirement in terms of Disk writes. On an >>> average when our application operates at a certain load i can observe that >>> the disk writes / second is around 2 Mbps (Average). >> >> Initial thought is, do you really care? 2Mbps is peanuts, so personally > The application workload is lot of small writes written and flushed. Is your application running fast enough? If so, I echo: do you really care? Let's suppose your application is not running fast enough. Is the disk drive a bottleneck? If not, you need to fix someting else. Let's suppose the disk drive is a bottleneck. Are your writes sequential? If so, I'd expect that drive internal caching would favor large block sizes, e.g. 2K. Since that is what you have, I expect your writes are not sequential. Find a way to make them sequential. The "and flush" is what will make that hard. Instead of writing X to location j in the main file, write (j, X) to the next sequential location to a cache file. When the cache has enough data, do an in-memory stable sort and start writing to the main file. Clear the cache file. Unless the cache file is larege enough, I expect that this will largely duplicate what the disk drive does internally. It might be simpler just to get a faster disk drive. -- Michael hennebry at web.cs.ndsu.NoDak.edu "Sorry but your password must contain an uppercase letter, a number, a haiku, a gang sign, a heiroglyph, and the blood of a virgin." -- someeecards