Re: Stress testing a Pi...

On 11/05/2024 09:53, The Natural Philosopher wrote:

Well it was always going to be a shot in the dark...:-)
 And I think I can confirm that a Pi4 cannot drive three SSDs over USB unaided.
As soon as I tried to rsync a new drive as a backup, via NFS, I started to get disk errors. On unrelated disks...not involved in the transfer.
 The PI4 had a TV card on it that gets pretty hot so I removed that to reduce load on the power supply, but significantly it made *no difference at all*.
 I hooked up a n HDMI screen to monitor the console messages and it was full of disk errors of one sort or another.
 Not necessarily related to the drive in use.
 My tentative conclusion, which I would like some opinion on, is that it is the USB power limit that is causing the problems, not the overall power draw. As that would have bee relieved by removing the TV hat.
 Now as far as I can tell the total USB power available on the PI4 equates to 1200mA.
 But on the Pi 5 that increase to 1600mA, provided you tell the board it has a 'high power supply'.
 

1600mA isn't that much more than 1200mA. There is quite a difference in the power requirements of different SSDs. Kingston A400 drives have a max wattage of about 1.5 watts. Some other SSD drives quote up to 5 watts. NVME drives even more.
So If I were you, I would want to understand the drives you have, know their power consumption, before making a decision.
FWIW, I only have one USB SSD running off an unpowered cable. The additional drives use a secondary power supply, but I use spinning HDDs as well as SSDs, so I needed to.
Also, the Pi 5 is a great computer, so worth buying just for fun. You'll find something to use it for.