🚀 Linux Bcache Monitor

A lightweight and fast Linux bcache monitoring tool for real-time performance analysis, IO statistics, and cache diagnostics.

Perfect for homelabs, servers, and SSD + HDD cache setups.

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✨ Features

• 📊 Real-time bcache statistics
• ⚡ Monitor SSD cache performance
• 💾 Analyze HDD + SSD hybrid setups
• 🧠 Simple CLI interface (no dependencies)
• 🔍 Detect IO bottlenecks
• 🐧 Works on all major Linux distributions

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📸 Preview

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🧩 What is bcache?

bcache is a Linux kernel block layer that allows using an SSD as a cache for slower HDDs.

This tool helps you monitor:

• Cache hit ratio
• IO throughput
• Device performance
• System bottlenecks

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🚀 Installation

This curl downloads the file to the current path and makes it executable immediately:

curl -fsSL https://raw.githubusercontent.com/fabianschmeltzer/Linux-Bcache-Monitor/main/bcache-monitor -o ./bcache-monitor && chmod +x ./bcache-monitor

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ℹ️ Info, credits, and legal notes

• Version: 0.6.00
• Credits: by Fabian Schmeltzer
• AI note: This program was written with AI assistance and may contain errors. Please verify critical output and use this tool at your own risk.
• Bug reports: Please submit bugs and improvement suggestions via GitHub Issues: https://github.com/fabianschmeltzer/Linux-Bcache-Monitor/issues
• Legal note: This is not legal advice. Without an explicit open-source license, standard copyright rules generally apply; GitHub documents that public repositories without a license can be viewed and forked on GitHub, but broader use, distribution, or derivative works require an appropriate license or permission. For binding guidance, consult legal counsel.

📖 What do the values mean?

• EFF: Cache efficiency from Total Hits / (Total Hits + Total Misses). Low values indicate many accesses are not served by SSD cache.
• DIRTY: Amount of data in cache that still needs to be written to the HDD/backing device. Especially important in writeback mode.
• MISS/HIT: Ratio of current misses per second to hits per second. Values around 1.0 or higher mean at least as many requests bypass cache as are served by it.
• LIVE HIT/s and MISS/s: Live per-second change rate of bcache counters.
• GRAPH: Red shows MISS/s, green shows HIT/s; ◆ marks the newest point, • older points.
• H/M current/avg/peak: Current value, window average, and peak value.
• MIX: Percentage share of current bcache events. M is miss share, H is hit share. With no load, the tool shows MIX idle because percentages would be misleading.
• Δ / DELTA: Comparison of current value with window average. If average is 0, n/a is shown.
• HEALTH: Traffic-light assessment from efficiency, miss/hit ratio, and miss trend.
• SSD cache / Avail WB: Cache size and potentially available cache share for writeback, when readable from sysfs.
• HDD/backing: Size of the bcache block device and, if mounted, used/free filesystem space.
• WB target: Background writeback rate (writeback_rate) reported by bcache in bytes/s. This is bcache's throttle/target rate and not necessarily identical to physical HDD I/O.
• WB percent / WB running: Target share for dirty data and status indicating whether bcache background writeback is running.
• HDD write: Real backing-device write rate calculated from /sys/block/<device>/stat between two samples. Helps show whether dirty data is actually draining to HDD.
• Docker DISK: Read and write rates from Docker BlockIO deltas since the last Docker refresh. The last calculated rate remains visible until a new Docker sample is available.

Reference sources: The Linux kernel documentation describes bcache sysfs values such as dirty_data, writeback_percent, writeback_rate, cache_available_percent, bucket_size, and nbuckets. GitHub Docs and Choose a License explain the legal baseline for repositories without a license.

⚖️ Legal note

This is not legal advice. The tool is provided without warranty; output may be incorrect, incomplete, or outdated. Independently verify critical values before production decisions. Without an explicit open-source license, standard copyright rules generally apply; public GitHub repositories may be viewed and forked under GitHub platform terms, but broader use, distribution, or derivative works require an appropriate license or permission.

🙏 Credits

by Fabian Schmeltzer

This program was written with AI assistance and may contain errors. Please report bugs at https://github.com/fabianschmeltzer/Linux-Bcache-Monitor/issues.