Why would a ~3GB database size consume 10+GB of server RAM?

[abed_halawi]

It is a causal cluster of 3 instances (1 leader 2 followers). Below are the sysinfo output:

Store Sizes
Count Store	35.00 KiB
Label Store	279.29 KiB
Index Store	717.59 MiB
Schema Store	200.01 KiB
Array Store	595.73 MiB
Logical Log	249.65 MiB
Node Store	51.67 MiB
Property Store	617.91 MiB
Relationship Store	69.67 MiB
String Store	499.27 MiB
Total Store Size	2.98 GiB

ID Allocation
Node ID	3610731
Property ID	15790448
Relationship ID	2116732
Relationship Type ID	321

Page Cache
Faults	324113
Evictions	0
File Mappings	165
Bytes Read	2652151457
Flushes	1714
Eviction Exceptions	0
File Unmappings	116
Bytes Written	14456456
Hit Ratio	99.99%
Usage Ratio	82.75%

Transactions
Last Tx Id	61236137
Current	1
Peak	2
Opened	20988
Committed	20987

Pagecache and Heap config:

• dbms.memory.heap.initial_size: 5G
• dbms.memory.heap.max_size: 5G
• dbms.memory.pagecache.size: 3G

Attached screenshot of consumption applies to all three instances the same.

[dana_canzano]

@abed_halawi   

a. what version of Neo4j

b.  your heap is defined to use 5G and pagecache is defined to use 3G and this would bring us to 8G.   But the JVM, just like any other JVM, does not thus only run on these 2 memory allocations.

Also I might ??? disagree with a dbms.memory.pagecache.size=3G for

Total Store Size

2.98 GiB

is a bit incorrect as this includes the size of all transaction logs, and transaction logs are not loaded into dbms.memry.pagecache.size.   Further

Logical Log

249.65 MiB

 is also a bit incorrect since it represents the size of the current written txn log ( data/graph.db/neostore.transaction.db*) but you may have multiple files here.   And the multiple files are incorrectly used in the 'Total Store Size'.   ``Incorrect`  in that transaction logs are not loaded into dbms.memory.pagecache.size

[abed_halawi]

Thank you @dana_canzano 

a. 3.5.4 (unfortunately couldn't upgrade yet)

b. Do you mean that I should increase pagecache and reduce heap instead? e.g. pagecache = 5G, heap = 3G?

[dana_canzano]

@abed_halawi 

a. Neo4j 3.5.x is no longer eligible for new patch releases

b. I would set pagecache to be the size, i.e. last line, as reported by `du -hc data/graph.db/*store.db`*`