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Document udev port-binding for two identical USB optical drives

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Drives on VL805 card get stable /dev/optical-drive1 and /dev/optical-drive2
symlinks via port-based udev rules. Explains why vendor/device ID binding
fails for identical drives.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
Claude
2026-06-27 17:37:00 +00:00
parent da02e6eebe
commit 5f10e2210b
1 changed files with 32 additions and 10 deletions
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@@ -2429,20 +2429,42 @@ qm set <vmid> -usb0 host=2-1 # bus-port notation from lsusb -t
**USB optical drives:**
Pass a USB optical drive to VM 100 (Services) for ripping with MakeMKV or
HandBrake. Use **Method B (by port)** rather than by vendor/device ID — some
optical drives briefly re-enumerate when a disc spins up, which can cause the
device to drop and reconnect if bound by ID.
Two USB optical drives connect to the VL805 PCIe card (already passed to VM 100
as a PCI device in Step 11.4b). The drives appear inside VM 100 as `/dev/sr0`
and `/dev/sr1` — but boot order can swap which is which.
**Fix: udev port-binding rules inside VM 100.**
Always plug drive 1 into the outermost port and drive 2 into the next port in.
Label the cables. Then create stable symlinks based on port path:
```bash
# Find the port your drive is on:
lsusb -t
# Then pass it to VM 100:
qm set 100 -usb2 host=<bus>-<port> # e.g. host=2-3
# Inside VM 100 — plug both drives in, then find their port paths
udevadm info /dev/sr0 | grep ID_PATH
udevadm info /dev/sr1 | grep ID_PATH
# Example output:
# E: ID_PATH=pci-0000:01:00.0-usb-0:1:1.0-scsi-0:0:0:0 ← outermost port
# E: ID_PATH=pci-0000:01:00.0-usb-0:2:1.0-scsi-0:0:0:0 ← next port in
# Create the udev rule (replace ID_PATH values with yours from above)
sudo tee /etc/udev/rules.d/99-optical.rules << 'EOF'
ENV{ID_PATH}=="pci-0000:01:00.0-usb-0:1:1.0*", SYMLINK+="optical-drive1"
ENV{ID_PATH}=="pci-0000:01:00.0-usb-0:2:1.0*", SYMLINK+="optical-drive2"
EOF
sudo udevadm control --reload-rules && sudo udevadm trigger
# Verify
ls -la /dev/optical-drive*
# Should show: optical-drive1 -> sr0 and optical-drive2 -> sr1
```
Inside VM 100 the drive appears as `/dev/sr0`. MakeMKV and HandBrake will
find it automatically.
Use `/dev/optical-drive1` and `/dev/optical-drive2` in MakeMKV and HandBrake
instead of `/dev/sr0` — these names survive reboots and port re-enumeration.
> **Why not bind by vendor/device ID?** Identical drives share the same vendor
> and device ID so udev can't tell them apart. Port binding is the only reliable
> method for two identical drives.
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