# NVMe Freeze Fix Plan — Kingston SNV2S2000G

## Problem
System freezes and SSHD becomes unresponsive due to NVMe I/O write timeouts.
The Kingston SNV2S2000G firmware fails to wake from deep power states (PS3/PS4) in time,
causing the kernel to abort I/O operations and eventually hard-lock the system.

- 152 NVMe I/O timeout errors logged in previous boot (Feb 17-20)
- 1 NVMe controller reset (Feb 19 09:41)
- 52 unsafe shutdowns (hard power-offs from freezes)
- SMART health: PASSED — drive is not failing, firmware power management is the issue

## Root Cause
NVMe Autonomous Power State Transition (APST) puts the drive into PS3/PS4.
Exit latencies (5ms / 70ms) exceed what the firmware can reliably handle,
causing write and flush operations to time out.

## Fix: Disable Deep NVMe Power States

### Step 1 — Apply kernel parameter

Run with sudo in a terminal:

```bash
sudo sed -i 's|rootfstype=btrfs|rootfstype=btrfs nvme_core.default_ps_max_latency_us=5000|' /boot/limine.conf
```

### Step 2 — Verify the change

```bash
grep nvme_core /boot/limine.conf
```

Every `cmdline:` line should now end with `nvme_core.default_ps_max_latency_us=5000`.

### Step 3 — Reboot

```bash
sudo reboot
```

### Step 4 — Confirm after reboot

```bash
# Verify kernel parameter is active
cat /proc/cmdline | grep nvme_core

# Monitor for NVMe errors (should show nothing new)
journalctl -b -k | grep -i 'nvme.*timeout'
```

## Monitoring

Watch for recurrence over the next few days:

```bash
# Check for any NVMe timeouts in current boot
journalctl -b -k | grep -i 'nvme.*timeout'

# Check SMART data periodically
sudo smartctl -a /dev/nvme0
```

## If Freezes Continue

1. Try a stricter latency limit: change `5000` to `0` (disables all power state transitions)
2. Check for Kingston firmware updates for SNV2S2000G (current: SBK00104)
3. If nothing helps, the drive may need replacement despite passing SMART checks

## Drive Info
- Model: KINGSTON SNV2S2000G (2TB)
- Serial: 50026B7784F6ACF9
- Firmware: SBK00104
- Percentage Used: 5%
- Bootloader: Limine
- Config: /boot/limine.conf