May 26, 2017 2:04 PM
173 Posts

What is a suboptimal ratio of Database.DbCache.Hit to Database.DbCache.Lookups?

  • Category: Domino Server
  • Platform: Windows
  • Release: 9.0.1
  • Role: Administrator
  • Tags: Domino performance tuning
  • Replies: 2

IBM says that the ratio of Database.DbCache.Hit to Database.DbCache.Lookups on a Domino server is a performance indicator.  If the ratio of Database.DbCache.Hit to "Database.DbCache.Lookups" is high, then the database cache is being effectively managed. 
If the ratio is low, then the server is in need of additional physical memory. My question is what is a low ratio?  Looking at ten of my servers, I see a range in percentages from .11 to .71.  Should I be concerned when the ratio is 1 to 2, or is the cutoff point higher or lower than that?  Six of the ten servers have a DBcache hit rate of 50% or less. 

 

May 30, 2017 9:55 AM
97 Posts
Depends...

It really depends on the workload of the server as databases will be flushed from the cache after 15-20 mins so if you have a server which is lightly used then a low hit rate would be normal.  If however it is a heavy use server then it could indicate server performance issues or just plain over worked.

Here's a good load of info to help with improving performance and the DBCache:

https://www.nashcom.de/nsh/web.nsf/ff5ce882e73ab026c1256942003bdf10/6084a81e9f2c2b00c1256cc30030c6c1/$FILE/bp106_final.pdf

May 30, 2017 6:31 PM
173 Posts
Thank you.

The ratio is high for the less used servers, and low for the heavily used. I will review the link to Daniel Nashed's presentation that you posted.