Better limiting on nextcloud, crossed things off todo.

modules/services/nextcloud.nix

@@ -18,6 +18,37 @@ let
   cfg     = config.homey.nextcloud;
   dataDir = config.homey.storage.mountPoint;
   domain  = homeyConfig.domain;
+
+  # Custom Nextcloud config mounted into the container as an extra config file.
+  # Nextcloud auto-loads all *.config.php files in /var/www/html/config/.
+  nextcloudCustomConfig = pkgs.writeText "zakobar.config.php" ''
+    <?php
+    $CONFIG = [
+      // Throttle preview generation during bulk uploads.
+      // Generating thumbnails re-reads every uploaded file and writes preview
+      // files, roughly doubling disk I/O.  Limiting concurrency to 1 prevents
+      // the drive from being hit by simultaneous read+write storms.
+      'preview_concurrency_new' => 1,
+      'preview_concurrency_all' => 1,
+      // Cap preview dimensions to reduce per-preview write size.
+      'preview_max_x' => 1024,
+      'preview_max_y' => 1024,
+      'jpeg_quality'  => 75,
+    ];
+  '';
+
+  # Limit Apache's prefork MPM so at most 4 PHP processes write to the USB
+  # drive simultaneously.  Default is often 150, which causes an I/O storm
+  # on slow USB HDDs.  Lower = fewer concurrent writers = more stable I/O.
+  apacheMpmConfig = pkgs.writeText "mpm_prefork.conf" ''
+    <IfModule mpm_prefork_module>
+        StartServers          2
+        MinSpareServers       1
+        MaxSpareServers       3
+        MaxRequestWorkers     4
+        MaxConnectionsPerChild 500
+    </IfModule>
+  '';
 in
 {
   options.homey.nextcloud = {
@@ -123,6 +154,10 @@ in
 
       volumes = [
         "${dataDir}/nextcloud/html:/var/www/html"
+        # Extra config auto-loaded by Nextcloud (throttles preview generation)
+        "${nextcloudCustomConfig}:/var/www/html/config/zakobar.config.php:ro"
+        # Apache MPM limits (caps concurrent PHP processes / disk writers)
+        "${apacheMpmConfig}:/etc/apache2/mods-available/mpm_prefork.conf:ro"
       ];
 
       extraOptions = [