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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 11:19:16 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-05 12:07:37 +0000 |
commit | b485aab7e71c1625cfc27e0f92c9509f42378458 (patch) | |
tree | ae9abe108601079d1679194de237c9a435ae5b55 /health/guides/disks/bcache_cache_errors.md | |
parent | Adding upstream version 1.44.3. (diff) | |
download | netdata-b485aab7e71c1625cfc27e0f92c9509f42378458.tar.xz netdata-b485aab7e71c1625cfc27e0f92c9509f42378458.zip |
Adding upstream version 1.45.3+dfsg.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'health/guides/disks/bcache_cache_errors.md')
-rw-r--r-- | health/guides/disks/bcache_cache_errors.md | 66 |
1 files changed, 0 insertions, 66 deletions
diff --git a/health/guides/disks/bcache_cache_errors.md b/health/guides/disks/bcache_cache_errors.md deleted file mode 100644 index 5256c480f..000000000 --- a/health/guides/disks/bcache_cache_errors.md +++ /dev/null @@ -1,66 +0,0 @@ -### Understand the alert - -This alert is triggered when the number of read races in the last minute on a `bcache` system has increased. A read race occurs when a `bucket` is reused and invalidated while it's being read from the cache. In this situation, the data is reread from the slower backing device. - -### What is bcache? - -`bcache` is a cache within the block layer of the Linux kernel. It enables fast storage devices, such as SSDs (Solid State Drives), to act as a cache for slower storage devices like HDDs (Hard Disk Drives). This creates hybrid volumes with improved performance. A cache device is usually divided into `buckets` that match the physical disk's erase blocks. - -### Troubleshoot the alert - -1. Verify the current `bcache` cache errors: - - ``` - grep bcache_cache_errors /sys/fs/bcache/*/stats_total/* - ``` - - This command will show the total number of cache errors for all `bcache` devices. - -2. Identify the affected backing device: - - You can determine the affected backing device by checking the `/sys/fs/bcache` directory. Look for the symbolic link that points to the problematic device. - - ``` - ls -l /sys/fs/bcache - ``` - - This command will show the list of devices with corresponding names. - -3. Monitor the cache device's performance: - - Use `iostat` to check the cache device's I/O performance. - - ``` - iostat -x -h -p /dev/YOUR_CACHE_DEVICE - ``` - - Note that you should replace `YOUR_CACHE_DEVICE` with the actual cache device name. - -4. Check the utilization of the cache and backing devices: - - Use the following commands to check the utilization percentage of the cache and backing devices: - - ``` - # for the cache device (/dev/YOUR_CACHE_DEVICE) - cat /sys/block/YOUR_CACHE_DEVICE/bcache/utilization - - # for the backing device (/dev/YOUR_BACKING_DEVICE) - cat /sys/block/YOUR_BACKING_DEVICE/bcache/utilization - ``` - - Replace `YOUR_CACHE_DEVICE` and `YOUR_BACKING_DEVICE` with the respective device names. - -5. Optimize the cache: - - - If the cache utilization is high, consider increasing the cache size or adding more cache devices. - - If the cache device is heavily utilized, consider upgrading it to a faster SSD. - - In case the read races persist, consider using a [priority caching strategy](https://www.kernel.org/doc/html/latest/admin-guide/bcache.html#priority-caching). - - You may also need to review your system's overall I/O load and adjust your caching strategy accordingly. - -### Useful resources - -1. [Bcache: Caching beyond just RAM](https://lwn.net/Articles/394672/) -2. [Kernel Documentation - Bcache](https://www.kernel.org/doc/html/latest/admin-guide/bcache.html) -3. [Arch Linux Wiki - Bcache](https://wiki.archlinux.org/title/bcache) -4. [Wikipedia - Bcache](https://en.wikipedia.org/wiki/Bcache) |