prometheus/node_exporter · error

couldn't get swap information

Error message

couldn't get swap information: %w

What it means

Update wrapped a failure from getSwapInfo (itself a procfs /proc/swaps read/parse failure) while gathering swap metrics. The whole swap scrape fails for the cycle; the root cause is in the underlying /proc/swaps access.

Solutions

1. Check /proc/swaps readability and format as for the underlying error.
2. Retry the scrape; transient read failures clear on the next cycle.
3. Disable the swap collector if the host has no swap support in its kernel.

When it happens

Trigger: Thrown at collector/swap_linux.go:81 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of prometheus/node_exporter@17ddd77c59 (2026-09-07). Data as JSON: /api/errors/aa9fcf69ff7e3e55. Report an issue: GitHub.

Appendix: source

Thrown at collector/swap_linux.go:81

	swaps, err := c.fs.Swaps()
	if err != nil {
		return nil, fmt.Errorf("couldn't get proc/swap information: %w", err)
	}

	metrics := make([]SwapsEntry, 0, len(swaps))

	for _, swap := range swaps {
		metrics = append(metrics, SwapsEntry{Device: swap.Filename, Type: swap.Type,
			Priority: swap.Priority, Size: swap.Size, Used: swap.Used})
	}

	return metrics, nil
}

func (c *swapCollector) Update(ch chan<- prometheus.Metric) error {
	swaps, err := c.getSwapInfo()
	if err != nil {
		return fmt.Errorf("couldn't get swap information: %w", err)
	}

	for _, swap := range swaps {
		swapLabelValues := []string{swap.Device, swap.Type}

		// Export swap size in bytes
		ch <- prometheus.MustNewConstMetric(
			prometheus.NewDesc(
				prometheus.BuildFQName(namespace, swapSubsystem, "size_bytes"),
				"Swap device size in bytes.",
				[]string{"device", "swap_type"}, nil,
			),
			prometheus.GaugeValue,
			// Size is provided in kbytes (not bytes), translate to bytes
			// see https://github.com/torvalds/linux/blob/fd94619c43360eb44d28bd3ef326a4f85c600a07/mm/swapfile.c#L3079-L3080
			float64(swap.Size*1024),
			swapLabelValues...,
		)

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