fix: use virtio serial for stable data disk discovery in PVC-backed w…

internal/workloads/chaos_disk.go

@@ -86,6 +86,11 @@ func (w *ChaosDiskWorkload) Name() string {
 func (w *ChaosDiskWorkload) CloudInitUserdata() (string, error) {
 	return w.BuildCloudConfig(CloudConfigOpts{
 		WriteFiles: []WriteFile{
+			{
+				Path:        "/usr/local/bin/virtwork-disk-setup.sh",
+				Content:     diskSetupScript("virtwork-chdisk", "/mnt/data"),
+				Permissions: "0755",
+			},
 			{
 				Path:        "/usr/local/bin/chaos-disk.sh",
 				Content:     chaosDiskScript,
@@ -98,7 +103,7 @@ func (w *ChaosDiskWorkload) CloudInitUserdata() (string, error) {
 			},
 		},
 		RunCmd: [][]string{
-			{"mkdir", "-p", "/mnt/data"},
+			{"/usr/local/bin/virtwork-disk-setup.sh"},
 			{"systemctl", "daemon-reload"},
 			{"systemctl", "enable", "--now", "virtwork-chaos-disk.service"},
 		},
@@ -116,7 +121,8 @@ func (w *ChaosDiskWorkload) DataVolumeTemplates() []kubevirtv1.DataVolumeTemplat
 func (w *ChaosDiskWorkload) ExtraDisks() []kubevirtv1.Disk {
 	return []kubevirtv1.Disk{
 		{
-			Name: "datadisk",
+			Name:   "datadisk",
+			Serial: "virtwork-chdisk",
 			DiskDevice: kubevirtv1.DiskDevice{
 				Disk: &kubevirtv1.DiskTarget{
 					Bus: "virtio",

internal/workloads/chaos_disk_test.go

@@ -115,10 +115,11 @@ var _ = Describe("ChaosDiskWorkload", func() {
 		Expect(dvts[0].Name).To(Equal("virtwork-chaos-disk-data"))
 	})
 
-	It("should have extra disk for data volume", func() {
+	It("should have extra disk for data volume with serial", func() {
 		disks := w.ExtraDisks()
 		Expect(disks).To(HaveLen(1))
 		Expect(disks[0].Name).To(Equal("datadisk"))
+		Expect(disks[0].Serial).To(Equal("virtwork-chdisk"))
 
 		volumes := w.ExtraVolumes()
 		Expect(volumes).To(HaveLen(1))
@@ -145,7 +146,28 @@ var _ = Describe("ChaosDiskWorkload", func() {
 		Expect(hasPackages).To(BeFalse())
 	})
 
-	It("should mount data disk and enable service via runcmd", func() {
+	It("should include disk-setup script in write_files", func() {
+		result, err := w.CloudInitUserdata()
+		Expect(err).NotTo(HaveOccurred())
+
+		parsed := parseYAML(result)
+		files := parsed["write_files"].([]interface{})
+
+		var setupContent string
+		for _, f := range files {
+			fm := f.(map[string]interface{})
+			if fm["path"] == "/usr/local/bin/virtwork-disk-setup.sh" {
+				setupContent = fm["content"].(string)
+				break
+			}
+		}
+		Expect(setupContent).NotTo(BeEmpty())
+		Expect(setupContent).To(ContainSubstring("virtio-virtwork-chdisk"))
+		Expect(setupContent).To(ContainSubstring("/mnt/data"))
+		Expect(setupContent).To(ContainSubstring("mkfs.xfs"))
+	})
+
+	It("should run disk-setup script and enable service via runcmd", func() {
 		result, err := w.CloudInitUserdata()
 		Expect(err).NotTo(HaveOccurred())
 
@@ -166,6 +188,7 @@ var _ = Describe("ChaosDiskWorkload", func() {
 			cmdStrings = append(cmdStrings, s)
 		}
 
+		Expect(cmdStrings).To(ContainElement(ContainSubstring("virtwork-disk-setup.sh")))
 		Expect(cmdStrings).To(ContainElement(ContainSubstring("daemon-reload")))
 		Expect(cmdStrings).To(ContainElement(ContainSubstring("virtwork-chaos-disk.service")))
 	})

internal/workloads/database.go

@@ -22,11 +22,27 @@ if [ -f "${MARKER}" ]; then
     exit 0
 fi
 
+# Discover the data disk by virtio serial
+DISK="/dev/disk/by-id/virtio-virtwork-dbdisk"
+for i in $(seq 1 30); do
+    [ -e "${DISK}" ] && break
+    sleep 1
+done
+if [ ! -e "${DISK}" ]; then
+    echo "ERROR: disk ${DISK} not found after 30s" >&2
+    exit 1
+fi
+REAL_DEV=$(readlink -f "${DISK}")
+
 # Format and mount the data disk
 if ! mountpoint -q "${DATA_DIR}"; then
-    mkfs.xfs /dev/vdc
-    mount /dev/vdc "${DATA_DIR}"
-    echo '/dev/vdc /var/lib/pgsql/data xfs defaults 0 0' >> /etc/fstab
+    if ! blkid -o value -s TYPE "${REAL_DEV}" > /dev/null 2>&1; then
+        mkfs.xfs "${REAL_DEV}"
+    fi
+    mount "${REAL_DEV}" "${DATA_DIR}"
+    if ! grep -q "${DATA_DIR}" /etc/fstab; then
+        echo "${REAL_DEV} ${DATA_DIR} xfs defaults,nofail 0 0" >> /etc/fstab
+    fi
 fi
 
 # Set ownership for postgres user
@@ -136,7 +152,8 @@ func (w *DatabaseWorkload) DataVolumeTemplates() []kubevirtv1.DataVolumeTemplate
 func (w *DatabaseWorkload) ExtraDisks() []kubevirtv1.Disk {
 	return []kubevirtv1.Disk{
 		{
-			Name: "datadisk",
+			Name:   "datadisk",
+			Serial: "virtwork-dbdisk",
 			DiskDevice: kubevirtv1.DiskDevice{
 				Disk: &kubevirtv1.DiskTarget{
 					Bus: "virtio",

internal/workloads/database_test.go

@@ -51,7 +51,7 @@ var _ = Describe("DatabaseWorkload", func() {
 		Expect(paths).To(ContainElement("/usr/local/bin/virtwork-db-setup.sh"))
 	})
 
-	It("should include setup script with initdb and pgbench init", func() {
+	It("should include setup script with serial discovery and initdb", func() {
 		result, err := w.CloudInitUserdata()
 		Expect(err).NotTo(HaveOccurred())
 
@@ -67,6 +67,7 @@ var _ = Describe("DatabaseWorkload", func() {
 			}
 		}
 		Expect(setupContent).NotTo(BeEmpty())
+		Expect(setupContent).To(ContainSubstring("virtio-virtwork-dbdisk"))
 		Expect(setupContent).To(ContainSubstring("postgresql-setup --initdb"))
 		Expect(setupContent).To(ContainSubstring("pgbench"))
 		Expect(setupContent).To(ContainSubstring("scale"))
@@ -142,10 +143,11 @@ var _ = Describe("DatabaseWorkload", func() {
 		Expect(dvts[0].Name).To(Equal("virtwork-database-data"))
 	})
 
-	It("should have extra disk for data volume", func() {
+	It("should have extra disk for data volume with serial", func() {
 		disks := w.ExtraDisks()
 		Expect(disks).To(HaveLen(1))
 		Expect(disks[0].Name).To(Equal("datadisk"))
+		Expect(disks[0].Serial).To(Equal("virtwork-dbdisk"))
 
 		volumes := w.ExtraVolumes()
 		Expect(volumes).To(HaveLen(1))

internal/workloads/disk.go

@@ -91,6 +91,11 @@ func (w *DiskWorkload) CloudInitUserdata() (string, error) {
 	return w.BuildCloudConfig(CloudConfigOpts{
 		Packages: []string{"fio"},
 		WriteFiles: []WriteFile{
+			{
+				Path:        "/usr/local/bin/virtwork-disk-setup.sh",
+				Content:     diskSetupScript("virtwork-disk", "/mnt/data"),
+				Permissions: "0755",
+			},
 			{
 				Path:        "/etc/fio/mixed-rw.fio",
 				Content:     fioMixedRWProfile,
@@ -108,7 +113,7 @@ func (w *DiskWorkload) CloudInitUserdata() (string, error) {
 			},
 		},
 		RunCmd: [][]string{
-			{"mkdir", "-p", "/mnt/data"},
+			{"/usr/local/bin/virtwork-disk-setup.sh"},
 			{"systemctl", "daemon-reload"},
 			{"systemctl", "enable", "--now", "virtwork-disk.service"},
 		},
@@ -126,7 +131,8 @@ func (w *DiskWorkload) DataVolumeTemplates() []kubevirtv1.DataVolumeTemplateSpec
 func (w *DiskWorkload) ExtraDisks() []kubevirtv1.Disk {
 	return []kubevirtv1.Disk{
 		{
-			Name: "datadisk",
+			Name:   "datadisk",
+			Serial: "virtwork-disk",
 			DiskDevice: kubevirtv1.DiskDevice{
 				Disk: &kubevirtv1.DiskTarget{
 					Bus: "virtio",

internal/workloads/disk_test.go

@@ -37,20 +37,21 @@ var _ = Describe("DiskWorkload", func() {
 		Expect(pkgs).To(ContainElement("fio"))
 	})
 
-	It("should include fio profiles in write_files", func() {
+	It("should include fio profiles and disk-setup script in write_files", func() {
 		result, err := w.CloudInitUserdata()
 		Expect(err).NotTo(HaveOccurred())
 
 		parsed := parseYAML(result)
 		files := parsed["write_files"].([]interface{})
 
-		// Should have: mixed-rw.fio, seq-write.fio, systemd unit = 3 files
-		Expect(files).To(HaveLen(3))
+		// Should have: disk-setup.sh, mixed-rw.fio, seq-write.fio, systemd unit = 4 files
+		Expect(files).To(HaveLen(4))
 
 		paths := make([]string, len(files))
 		for i, f := range files {
 			paths[i] = f.(map[string]interface{})["path"].(string)
 		}
+		Expect(paths).To(ContainElement("/usr/local/bin/virtwork-disk-setup.sh"))
 		Expect(paths).To(ContainElement("/etc/fio/mixed-rw.fio"))
 		Expect(paths).To(ContainElement("/etc/fio/seq-write.fio"))
 		Expect(paths).To(ContainElement("/etc/systemd/system/virtwork-disk.service"))
@@ -62,16 +63,38 @@ var _ = Describe("DiskWorkload", func() {
 		Expect(dvts[0].Name).To(Equal("virtwork-disk-data"))
 	})
 
-	It("should have extra disk for data volume", func() {
+	It("should have extra disk for data volume with serial", func() {
 		disks := w.ExtraDisks()
 		Expect(disks).To(HaveLen(1))
 		Expect(disks[0].Name).To(Equal("datadisk"))
+		Expect(disks[0].Serial).To(Equal("virtwork-disk"))
 
 		volumes := w.ExtraVolumes()
 		Expect(volumes).To(HaveLen(1))
 		Expect(volumes[0].Name).To(Equal("datadisk"))
 	})
 
+	It("should include disk-setup script with serial discovery", func() {
+		result, err := w.CloudInitUserdata()
+		Expect(err).NotTo(HaveOccurred())
+
+		parsed := parseYAML(result)
+		files := parsed["write_files"].([]interface{})
+
+		var setupContent string
+		for _, f := range files {
+			fm := f.(map[string]interface{})
+			if fm["path"] == "/usr/local/bin/virtwork-disk-setup.sh" {
+				setupContent = fm["content"].(string)
+				break
+			}
+		}
+		Expect(setupContent).NotTo(BeEmpty())
+		Expect(setupContent).To(ContainSubstring("virtio-virtwork-disk"))
+		Expect(setupContent).To(ContainSubstring("/mnt/data"))
+		Expect(setupContent).To(ContainSubstring("mkfs.xfs"))
+	})
+
 	It("should not require service", func() {
 		Expect(w.RequiresService()).To(BeFalse())
 		Expect(w.ServiceSpec()).To(BeNil())

internal/workloads/workload.go

@@ -4,6 +4,8 @@
 package workloads
 
 import (
+	"fmt"
+
 	corev1 "k8s.io/api/core/v1"
 	kubevirtv1 "kubevirt.io/api/core/v1"
 
@@ -116,6 +118,46 @@ func (b *BaseWorkload) VMCount() int {
 	return b.Config.VMCount
 }
 
+func diskSetupScript(serial, mountPoint string) string {
+	return fmt.Sprintf(`#!/bin/bash
+set -euo pipefail
+
+DISK="/dev/disk/by-id/virtio-%s"
+MOUNT_POINT="%s"
+
+# Wait for the disk symlink to appear (udev may be slow)
+for i in $(seq 1 30); do
+    [ -e "${DISK}" ] && break
+    sleep 1
+done
+
+if [ ! -e "${DISK}" ]; then
+    echo "ERROR: disk ${DISK} not found after 30s" >&2
+    exit 1
+fi
+
+# Resolve the symlink to the real block device
+REAL_DEV=$(readlink -f "${DISK}")
+
+mkdir -p "${MOUNT_POINT}"
+
+# Format only if no filesystem exists
+if ! blkid -o value -s TYPE "${REAL_DEV}" > /dev/null 2>&1; then
+    mkfs.xfs "${REAL_DEV}"
+fi
+
+# Mount if not already mounted
+if ! mountpoint -q "${MOUNT_POINT}"; then
+    mount "${REAL_DEV}" "${MOUNT_POINT}"
+fi
+
+# Ensure fstab entry for persistence across reboots
+if ! grep -q "${MOUNT_POINT}" /etc/fstab; then
+    echo "${REAL_DEV} ${MOUNT_POINT} xfs defaults,nofail 0 0" >> /etc/fstab
+fi
+`, serial, mountPoint)
+}
+
 // BuildCloudConfig injects SSH credentials into the given options and delegates
 // to cloudinit.BuildCloudConfig. Workloads should call this instead of the
 // package-level function to ensure consistent SSH credential handling.