From: tnp@invalid.invalid   
      
   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'.   
      
   I believe there is a config.txt option to do  that. Even if you don't   
   have the 'approved' PSU.   
      
   So I am thinking of going to a PI 5 rather than a separately powered USB   
   adapters for the drives - the other way to  increase power to the drives.   
      
   Or is there a better one board computer alternative?   
      
   I want to build everything into a small 19" case with an ethernet switch   
     board and OSUs to reduce clutter   
      
   --   
   Of what good are dead warriors? … Warriors are those who desire battle   
   more than peace. Those who seek battle despite peace. Those who thump   
   their spears on the ground and talk of honor. Those who leap high the   
   battle dance and dream of glory … The good of dead warriors, Mother, is   
   that they are dead.   
   Sheri S Tepper: The Awakeners.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)