Here are some recent experiences with flash storage on a Pi4 as a development environment running LinuxCNC 2.8.2.
A while back I posted in this mailing list that using an SSD on the Pi4 is prohibitive because it causes latency issues. At the time, I tested this on a heavily used, repurposed ssd. I later discovered that the SSD was failing due to write wear. This is likely what caused the latency issues in the first place. In the meantime I ran the Pi4 (2GB memory) as a development platform, running up to 3 instances of VS Code (1.5GB memory each) along with Glade, browser, etc. This type of usage made short work of the Samsung EVO microSD card. The card wear issue first showed up as spurious latency violations. A bit later the entire system became maddeningly slow and unusable. Cloning to a fresh sd card solved the problem. In the process of making backups I also cloned the system to an SSD (intel 320 this time) and to my surprise, it ran with zero latency issues. I will be using SSDs from now on, thank you. Some takeaways: 1) large page files are bad news for cheap flash storage 2) "worn out" storage will cause latency issue on low latency systems 3) latency tests on a low latency system might be a way to detect flash write wear issues. Thaddeus _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
