On 6/30/22 10:47, Thaddeus Waldner wrote:
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
This corresponds to my findings re the size of the u-sd, I've had zero
u-sd problems
since I switched to a fast 64G u-sd. Even with the traffic of keeping up
with the buildbot,
about 65 megs re-written daily, its survived nicely for 2+ years now.
Give this stuff
room to do its own maintenance and it Just Works.
I also have 2 SSD's plugged into usb3 adapters, one of 120G, and one of
240G that
I do buildbot or kernel building type work on, only problem I've ever
had there was a
bad, non-StarTech usb3 adapter, replaced the adapter, the SSD was fine.
Been running that way in addition to teaching my 80 yo Sheldon 11x54
tricks it never
dreamed of doing when it shipped 80 years ago with all the taper
accessories. Now
removed I might add along with a badly broken compound, now a block of
cast for
the correct tool height.
LinuxCNC does it better, including way wear comp, curved tapers, etc.
Thanks all.
Cheers, Gene Heskett.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/>
_______________________________________________
Emc-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/emc-users
