Hi Mark,

What I was referring to is:

"nsslapd-cache-autosize-split

The value sets the percentage of RAM that is used for the database cache. The 
remaining percentage is used for the entry cache.
More than 512 MB RAM database cache do not improve the performance. Therefore, 
the database cache is limited to 512 MB." - 
https://access.redhat.com/documentation/en-us/red_hat_directory_server/10/html-single/performance_tuning_guide/index#tuning-dbs-for-searches
Then further down is a table that tops off at 512MB for dbcache in the same 
document.  But even further down it contradicts by suggesting the results of 
the dbmon.sh script can provide insight into how much more the dbcache can be 
to improve performance with the 2.2% free example.
All these tuning features are great, but gets confusing when trying to mix and 
match the best combination of settings.
I did go over your recommendations and have settled for now on increasing the 
dbcache to 5GB.  Our consumers are configured with 64GB and the masters 128GB.  
While the percentage of free space in the dbcache is not optimal (more than 
12%), we are achieving a hit ratio of 99%.


Paul M. Whitney, RHCSA, CISSP
Chesapeake IT Consulting, Inc.
2680 Tobacco Rd
Chesapeake Beach, MD 20732

Work: 443-492-2872
Cell:   410.493.9448
Email: paul.whit...@chesapeake-it.com<mailto:paul.whit...@chesapeake-it.com>
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________________________________
From: Mark Reynolds <mreyno...@redhat.com>
Sent: Tuesday, July 16, 2019 9:30 AM
To: General discussion list for the 389 Directory server project.; Paul Whitney
Subject: Re: [389-users] Recommended SLAPD cache sizes


Hi Paul,


On 7/16/19 9:16 AM, Paul Whitney wrote:
Is there some formula or recommendation on determining what would be the 
optimal cache settings for a directory server (389-ds of course) with following 
sizes? I looked at the DS 10 Admin Guide online and am getting conflicting 
information.  But the manual shows a table and suggests that the max size for 
the cn=config dbcache is 512MB.
There is no limit on the cache size value besides what you are limited to by a 
unsigned long integer.  Do you have a link to where it says 512 MB is a maximum?
  But I tried with 5GB and it appears to work fine with it, although over time 
start to see negative values (prob not enough cache) and roevicts while running 
the dbmon.sh script.

__db files = ~6GB
groupRoot = 1.5GB
userRoot = 20GB

What values would yield best performance for:

cn=config dbcache? currently set to 5GB but are still seeing lots of roevicts. 
As much

userRoot entry cache? currently set to 21GB (hit ratio so far at 95%)

groupRoot entry cache? currently set to 2GB (hit ration so far at 96%)

Virtual machine configured with 8CPU, 128GB RAM. Load is in the low 20's with 
occasional spikes to high 20's.

If you have 128 GB available to you then I would continue to increase the cache 
sizes until you get to 99% hit ratio for the two entry caches, and the db 
cache.  Also make sure the DN and NDN caches also have a 99% cache hit ratio:


https://access.redhat.com/documentation/en-us/red_hat_directory_server/10/html/performance_tuning_guide/tuning-dn-cache


https://www.port389.org/docs/389ds/design/normalized-dn-cache.html




I would also look into running the DB on a RAM disk since you have the 
resources to do so:


https://access.redhat.com/documentation/en-us/red_hat_directory_server/10/html/performance_tuning_guide/tuning-db-cache#db-cache-on-ram-disk



HTH,

Mark



Paul M. Whitney, RHCSA, CISSP
Chesapeake IT Consulting, Inc.
2680 Tobacco Rd
Chesapeake Beach, MD 20732

Work: 443-492-2872
Cell:   410.493.9448
Email: paul.whit...@chesapeake-it.com<mailto:paul.whit...@chesapeake-it.com>
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The information contained in this facsimile or electronic message is 
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of this communication is strictly prohibited. If this message contains 
non-public personal information about any consumer or customer of the sender or 
intended recipient, you are further prohibited under penalty of law from using 
or disclosing the information to any third party by provisions of the federal 
Gramm-Leach-Bliley Act. If you have received this facsimile or electronic 
message in error, please immediately notify us by telephone and return or 
destroy the original message to assure that it is not read, copied, or 
distributed by others.




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