Details
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Bug
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Resolution: Incomplete
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Major - P3
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None
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None
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None
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ALL
Description
I have a 32 GB WT server running 3.0.8
The "bytes in cache" always seem to hover around ~1GB even though I have configured the cache size to be around ~26GB.
The total data size is around 40GB. Why is the rest of the cache not being used?
> db.serverStatus().wiredTiger.cache
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{
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"tracked dirty bytes in the cache" : 0,
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"tracked bytes belonging to internal pages in the cache" : 27634342,
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"bytes currently in the cache" : 950556531,
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"tracked bytes belonging to leaf pages in the cache" : 27889653082,
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"maximum bytes configured" : 27917287424,
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"tracked bytes belonging to overflow pages in the cache" : 0,
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"bytes read into cache" : 17875008775,
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"bytes written from cache" : 120063944822,
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"pages evicted by application threads" : 0,
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"checkpoint blocked page eviction" : 4,
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"unmodified pages evicted" : 0,
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"page split during eviction deepened the tree" : 1,
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"modified pages evicted" : 90924,
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"pages selected for eviction unable to be evicted" : 20,
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"pages evicted because they exceeded the in-memory maximum" : 1289,
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"pages evicted because they had chains of deleted items" : 14418,
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"failed eviction of pages that exceeded the in-memory maximum" : 15,
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"hazard pointer blocked page eviction" : 6,
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"internal pages evicted" : 0,
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"maximum page size at eviction" : 10499573,
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"eviction server candidate queue empty when topping up" : 1241,
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"eviction server candidate queue not empty when topping up" : 3,
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"eviction server evicting pages" : 0,
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"eviction server populating queue, but not evicting pages" : 1243,
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"eviction server unable to reach eviction goal" : 0,
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"pages split during eviction" : 1374,
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"pages walked for eviction" : 55451388,
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"eviction worker thread evicting pages" : 2086,
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"in-memory page splits" : 1238,
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"percentage overhead" : 8,
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"tracked dirty pages in the cache" : 0,
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"pages currently held in the cache" : 16807,
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"pages read into cache" : 2583552,
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"pages written from cache" : 7389684
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}
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The only thing special about this server is that it has a large number of dbs, around 4k. Each db has around 3 collections.