I spent some more time today comparing InnoDB and MyISAM on SSD. I increased the data/cache ratio by about 5X. I allocated 1G of memory for MyISAM or InnoDB (restating MySQL after each test). Resulting on disk images are 6G for MyISAM and 7G for InnoDB. This is on a 30M row DB which stores [...]
Categories: clustering,linux,memcached,mysql,open source,SSD
The other night I was thinking about MySQL cluster and whether or not a high speed interconnect would be worth the investment. Doing some research lead me to the conclusion that Ethernet latency isn’t discussed very often except in niche mailing list threads.
Categories: linux,memcached,mysql,open source
Objects would not serialize themselves before storage so this should act like an ultrafast LRU cache as if it were a native caching system within the VM.Since it’s a local it should be MUCH faster than the current memcached.Here are some benchmarks of APC-cache vs memcached.http://www.mysqlperformanceblog.com/2006/09/27/apc-or-memcached/http://www.mysqlperformanceblog.com/2006/08/09/cache-performance-comparison/Long story short a local cache can be 4-8x faster than normal memcached.The local in-process cache would be available on every node within this cluster and act as a L1 cache for ultra fast access to a small number of objects.I’m not sure all languages would support this type of cache because it would require access to and storage of object pointers…. There are a number of memcached implementations (including the Java impl which I’ve contributed to) This would provide ultra high capacity and since the disk seeks are distributed over a large number of disks you can just add spindles to the equation to get higher throughput.This system would also NOT suffer from disk hotspots since memcached and the local in-memory memcached would buffer the disk backend.From a non-theoretical perspective the local cache could be skipped or replaced with a native LRU cache.
I’ve been looking at a problem with our memory cache system at work for the last week and the problem finally clicked into place.At work I developed this really awesome benchmarking library which exports statistics from various subsystems in my robot. It works really well – too well sometimes.Its been telling me that one of my caches is only functioning at 20% efficiency.