Hi everybody, I've a performance issue on my CouchDB servers.
My OS is a FreeBSD-8.3 with ZFS. My ZFS pool is a raid10 array (two concatenated mirror), using four 7.2K SATA Disk and a SSD for the ZIL (== write cache). I'm using CouchDB-1.2.0. My database, before compaction, is 1TB with 91M documents. CouchDB says there is 90GB of data (~1KB per doc). When running compaction, CouchDB takes very little CPU (~20% of one processor for beam.smp) and reads very slowly: 800KB/s (~200KB/s per disk, small transactions rate). Compaction takes days... That is really strange because I'm able to read my full database, with dd, at a better speed: 80MB/s (~20MB/s per disk and bigger transactions rate) not perfect but quicker than CouchDB. What can make CouchDB read so slowly ? Does anybody have an idea about this slowness ? thank you for your help. Best, jym PS: We plan to use CouchDB in a write-heavy application: 500 doc inserted by seconds, only one simple view. Servers will be bigger (12 or 24 disks, SSD for cache) and the bigcouch merge will be a great help but we need better performance on a single node while waiting the 2.0 release :-)
