GCP CDN cache-miss granularity

Question

I'm trying to make an accurate estimate of CDN usage on Google Cloud Platform but am not sure about the fill costs.

Fill costs are incurred on a cache miss and the data is gotten from origin or another cache. What's not specifically mentioned is how granular a "cache" miss is. That is - is it a cache miss for the region? zone? POP? node?

With an international distribution this could be make a huge difference in estimation.

score 0 · Answer 1 · answered Dec 12 '17 at 15:19

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According to the official documentation, cache fill charges vary based on source and destination. Source is the region of the origin server or, in the case of cache-to-cache cache fill, the region of the source cache. Destination is a geographic area determined by client IP address. link

answered Dec 12 '17 at 15:19

miguelfrancisco85

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What you say is correct, but it does not say the max number of cache fills you could have. I asked google directly and answered the original question with it separately. – buckaroo1177125 Dec 15 '17 at 06:12

score 0 · Accepted Answer · answered Dec 15 '17 at 06:10

I asked Google support directly on this one and got back that cache fills occur in each "cache site." Or as they put it:

Cache fill is counted for each caching sites since cache fill occured between one cache location to another cache location.

The updated list of cache sites/locations is in their documentation.

At the time of writing that means a hypothetical max of 81 cache fills for a given result (not including expiring or being pushed out of the cache and re-filling etc.) - presuming your content is requested from each of these location as the cache is only filled when requested.

GCP CDN cache-miss granularity

2 Answers2