Increase SpectroSERVER DB cache to improve performance

Products

• CA Spectrum

Issue/Introduction

The SpectroSERVER Database (BerkeleyDB) cache size is the single most important configuration parameter.  The SpectroSERVER DB cache size is initialized to 10Meg since Spectrum 6.x and it’s far too low for 64-bit Spectrum deployments. For all supported versions, we would suggest customers to set the vnmrc option ssdb_cache_size_kbytes=524288 for a better performance.

Environment

Spectrum 10.2.x and up

Cause

64-bit Spectrum Deployments need larger DB cache for better performance.

Resolution

SpectroSERVER DB cache can be set by using a parameter for the .vnmrc VNM config file. Set the db cache size to 512MB (524288 bytes): 

<SPECROOT>/SS/.vnmrc

ssdb_cache_size_kbytes=524288

 

Note - The db cache size was tested up to 990Meg and the results hold up well. HOWEVER Do not set the cache size to 1Gig or higher as that will cause the DB to throw errors on insufficient space.

 

A SpectroSERVER Restart is then required to properly set memory on startup. 

 

 

Additional Information

Spectrum 10.5 will come with Berkeley DB cache set to 512MB by default.

 

If you are curious about the DB stats, you can print this out in CLI: 

./update action=0x10323 mh=<vnm mh>

 

• this cache increase has been seen to approve the cache hit ratio performance
• the SpectroSERVER will allocate additional memory at startup to account for the increased cache size