Archived Forum

Thanks Robert this is really interesting, emoncms.org write load measured with iotop -a is currently running at about 2.2MB/s (1189.54 MB/s in 9 mins) thats with 13000 feeds with an average update rate of 20s , on two 240GB MLC SSD's in raid 1. Which equates to around 66TB/year.

Thats without the low write load optimisations used on the low write sd card which could reduce this by ~5-10x https://github.com/openenergymonitor/documentation/blob/master/BuildingB...

I plan to add the low write features in to the full emoncms once I work out the best way to request data for viewing across both the buffer and the disk simultaneously.

thanks for sharing this.

Edit: I should note for anyone interested that the 66TB/year is not data accumulation, write load is much higher than data accumulation due to the way data is written to disk in blocks that are much larger 4096 bytes say vs the 4 bytes of actual data accumulation. This is why buffering provides such an improvement because your data write size can become nearer to the block size.