Sharepoint Blob Cache Fill Ratio question

Question

Per MS documentation: https://learn.microsoft.com/en-us/sharepoint/administration/monitor-cache-performance

Blob Cache Fill Ratio should be under 80% for optimal performance.
Above 90% might indicate that the cache size is too small.

At first we had the default cache size 10GB and noticed from PerfMon that Blob Cache Fill Ratio is nearly 200% at maximum and average is always greater than 100% at office hours.

Then we allocated more space to the disk 10GB -> 30GB and also made the change to webconfig.

Fill Ratio numbers doesn't change and there's still ~15GB space left on the Blob Cache drive.

Allocated more space to the drive 30GB -> 60GB and made the change to webconfig and still no change. Same ratio and there's ~45GB space left on the Blob Cache drive.

Cache hits and Cache miss counts are good, but I don't understand why won't that Fill Ratio decrease even there is more than enough space on the cache drive.

Answer 1

Hi anonymous user,

Allocated more space to the drive 30GB -> 60GB

Have you changed BLOB cache size? From this article Plan for caching and performance in SharePoint Server: You have to allow at least 20 percent more space on the drive than the size of the cache. For example, if you have 100 GB of content, set the size of the cache to 120 GB on a drive that has at least 150 GB of space. If the BLOB cache is too small, serving files to users slows, reducing the performance of your site.

To change the size of the cache, you could type a new number for maxSize in web.config file.

For Reference: Configure BLOB cache settings

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