From: Pancho.Jones@proton.me   
      
   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.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)