Stop calling an empty parity slot an emulated disk

mdNumDisabled counts a slot that was never populated, so HOST2 reported
"Emulating 1 disk" for a parity2 slot with no disk in it. Emulation is a
data-disk state, and an assigned identity is what separates a slot that lost
its disk from one that never had one.

Plugin/unraid/include/common.php

@@ -517,6 +517,48 @@ function vv_parity_status(): array {
     $numMissing  = (int)($var['mdNumMissing']  ?? 0);
     $exitCode    = (int)($var['sbSyncExit'] ?? 0);
     $errors      = (int)($var['sbSyncErrs'] ?? 0);
+
+    // How many disks are actually being emulated, which is not mdNumDisabled.
+    //
+    // mdNumDisabled counts every slot the array marks disabled, including a parity slot that was
+    // never populated. HOST2 reports mdNumDisabled=1 with mdNumMissing=0, and the slot is parity2
+    // at DISK_NP_DSBL — an empty second-parity slot. Unraid's own Main page shows nothing for it,
+    // while this card said "Emulating 1 disk" and turned the banner amber.
+    //
+    // Parity is never emulated: reconstructing a parity disk from parity is not a thing. Only data
+    // slots are, so the count is taken from disks.ini and restricted to them. A data disk that is
+    // disabled *is* emulated whether or not it is physically present — a pulled failed drive reads
+    // DISK_NP_DSBL and is genuinely being served from parity — so presence is not the test here,
+    // role is.
+    //
+    // A disabled parity slot is still worth knowing about when a real parity disk fails, so it is
+    // counted separately rather than discarded.
+    //
+    // Both counts require the slot to have an assigned identity. A slot that was never populated
+    // reads id="" device="" size="0" — parity2 on HOST2 is exactly that — while a disk that failed
+    // and was pulled keeps its id, because the array remembers the assignment it is emulating.
+    // Presence is therefore the wrong test and identity is the right one: it separates "no disk was
+    // ever here" from "the disk that belongs here is gone", which look identical in the status
+    // field alone and mean opposite things.
+    $numEmulated = 0;
+    $numParityDisabled = 0;
+    $slot = ''; $slotId = ''; $slotStatus = '';
+    $tally = function () use (&$slot, &$slotId, &$slotStatus, &$numEmulated, &$numParityDisabled) {
+        if ($slot === '' || $slotId === '') return;
+        if (strpos($slotStatus, 'DSBL') === false) return;
+        if (preg_match('/^disk\d+$/', $slot))        $numEmulated++;
+        elseif (preg_match('/^parity\d*$/', $slot))  $numParityDisabled++;
+    };
+    foreach (@file('/var/local/emhttp/disks.ini') ?: [] as $line) {
+        if (preg_match('/^\["([^"]+)"\]/', $line, $m)) {
+            $tally();                                   // close the previous slot
+            $slot = $m[1]; $slotId = ''; $slotStatus = '';
+            continue;
+        }
+        if (preg_match('/^id="([^"]*)"/', $line, $m))     $slotId     = trim($m[1]);
+        if (preg_match('/^status="([^"]*)"/', $line, $m)) $slotStatus = $m[1];
+    }
+    $tally();                                           // and the last one, which has no header after it
     // Emulated (DISK_DSBL) disks are protected by parity and don't make parity invalid.
     // True invalidity: sync errors on the last check, or unprotectable missing slots.
     $isValid     = $errors === 0 && $numMissing === 0;
@@ -566,7 +608,12 @@ function vv_parity_status(): array {
     $exitMap = ['0' => 'Completed', '-4' => 'Aborted', '-5' => 'Cancelled'];
     return [
         'valid'         => $isValid,
+        // mdNumDisabled as the array reports it, kept because it is Unraid's own number and
+        // anything comparing against the WebGUI wants it. Not what the card labels, though —
+        // num_emulated is the one that means "data is being served from parity".
         'num_disabled'  => $numDisabled,
+        'num_emulated'      => $numEmulated,
+        'num_parity_disabled' => $numParityDisabled,
         'num_missing'   => $numMissing,
         'in_progress'     => $inProgress,
         'resync_action'   => $resyncAction,

Plugin/unraid/pages/monitor.php

@@ -1290,21 +1290,28 @@ function vvPollMonitor(live) {
           return new Date(ts * 1000).toLocaleString([], {weekday:'short',day:'numeric',month:'short',year:'numeric',hour:'2-digit',minute:'2-digit'});
         }
 
-        const numDisabled  = par.num_disabled ?? 0;
+        // num_emulated, not num_disabled: the array counts an empty parity slot as disabled, and
+        // labelling that "Emulating 1 disk" described a failure that was not happening. See
+        // vv_parity_status() for why parity slots are counted separately.
+        const numEmulated  = par.num_emulated ?? 0;
+        const numParityDsbl = par.num_parity_disabled ?? 0;
         const numMissing   = par.num_missing  ?? 0;
-        const degraded     = numDisabled > 0 || numMissing > 0;
+        const degraded     = numEmulated > 0 || numMissing > 0;
         const exitColor    = par.exit_label === 'Completed' ? '#4caf50' : par.exit_label === 'Aborted' ? '#ff9800' : '#f44336';
         const errColor     = (par.errors ?? 0) > 0 ? '#f44336' : '#444';
         const speedStr     = par.last_speed_mb ? ` · ${par.last_speed_mb} MB/s` : '';
         const nextDate     = vvFmtDate(par.next_ts);
         const dueIn        = vvDueIn(par.next_ts);
         const parBannerCls = !valid ? 'vv-banner-err' : degraded || (par.errors ?? 0) > 0 ? 'vv-banner-warn' : 'vv-banner-ok';
-        const emulLabel    = numDisabled > 0 ? `<span style="font-size:11px;">Emulating ${numDisabled} disk${numDisabled !== 1 ? 's' : ''}</span>` : '';
+        const emulLabel    = numEmulated > 0 ? `<span style="font-size:11px;">Emulating ${numEmulated} disk${numEmulated !== 1 ? 's' : ''}</span>` : '';
         const missingLabel = numMissing  > 0 ? `<span style="font-size:11px;color:#f44336;">${numMissing} slot${numMissing !== 1 ? 's' : ''} missing</span>` : '';
+        // A failed parity disk is a real fault and still has to surface — it just is not emulation,
+        // and it does not mean data is being reconstructed.
+        const parDsblLabel = numParityDsbl > 0 ? `<span style="font-size:11px;color:#ffb74d;">${numParityDsbl} parity disk${numParityDsbl !== 1 ? 's' : ''} disabled</span>` : '';
 
         let html = `<div class="vv-banner ${parBannerCls}">
           <span>${valid ? '✓ Valid' : '✗ INVALID'}</span>
-          ${emulLabel}${missingLabel}
+          ${emulLabel}${missingLabel}${parDsblLabel}
           ${(par.errors ?? 0) > 0 ? `<span style="font-size:11px;">${par.errors} error${par.errors !== 1 ? 's' : ''}</span>` : ''}
         </div>`;