question Re: Error during add datanode service in Archives of Support Questions (Read Only)

Error during add datanode service

i9um0 — Fri, 16 Sep 2022 09:15:44 GMT

Hi All,

we met following error below when adding datanode services which in previously never happen at our cluster.

Path: http://hostnamexxxxx:7180/cmf/services/25/addRole/checkDbTestConn

Version: Cloudera Express 5.2.0 (#60 built by jenkins on 20141012-2239 git: 179000584849e68f98ad2a7fe710723bd6c29c98)

java.lang.RuntimeException:Failed to fetch embedded db users
at DbUtil.java line 686
in com.cloudera.enterprise.dbutil.DbUtil fetchEmbeddedDbUsers()

Stack Trace:

DbUtil.java line 686
in com.cloudera.enterprise.dbutil.DbUtil fetchEmbeddedDbUsers()
DbTestConnUtil.java line 340
in com.cloudera.server.web.cmf.DbTestConnUtil populateDbTestConnInfos()
AddRoleWizard.java line 244
in com.cloudera.server.web.cmf.wizard.service.AddRoleWizard getTestDatabaseData()
GenericAddRoleWizardController.java line 330
in com.cloudera.server.web.cmf.wizard.service.GenericAddRoleWizardController getDbSetupData()
<generated> line -1
in com.cloudera.server.web.cmf.wizard.service.GenericAddRoleWizardController$$FastClassByCGLIB$$3016baee invoke()
MethodProxy.java line 191
in net.sf.cglib.proxy.MethodProxy invoke()
Cglib2AopProxy.java line 688
in org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation invokeJoinpoint()
ReflectiveMethodInvocation.java line 150
in org.springframework.aop.framework.ReflectiveMethodInvocation proceed()
MethodSecurityInterceptor.java line 61
in org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor invoke()
ReflectiveMethodInvocation.java line 172
in org.springframework.aop.framework.ReflectiveMethodInvocation proceed()
Cglib2AopProxy.java line 621
in org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor intercept()
<generated> line -1
in com.cloudera.server.web.cmf.wizard.service.GenericAddRoleWizardController$$EnhancerByCGLIB$$69955bfd getDbSetupData()
NativeMethodAccessorImpl.java line -2
in sun.reflect.NativeMethodAccessorImpl invoke0()
NativeMethodAccessorImpl.java line 57
in sun.reflect.NativeMethodAccessorImpl invoke()
DelegatingMethodAccessorImpl.java line 43
in sun.reflect.DelegatingMethodAccessorImpl invoke()
Method.java line 606
in java.lang.reflect.Method invoke()
HandlerMethodInvoker.java line 176
in org.springframework.web.bind.annotation.support.HandlerMethodInvoker invokeHandlerMethod()
AnnotationMethodHandlerAdapter.java line 436
in org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter invokeHandlerMethod()
AnnotationMethodHandlerAdapter.java line 424
in org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter handle()
DispatcherServlet.java line 790
in org.springframework.web.servlet.DispatcherServlet doDispatch()
DispatcherServlet.java line 719
in org.springframework.web.servlet.DispatcherServlet doService()
FrameworkServlet.java line 669
in org.springframework.web.servlet.FrameworkServlet processRequest()
FrameworkServlet.java line 574
in org.springframework.web.servlet.FrameworkServlet doGet()
HttpServlet.java line 707
in javax.servlet.http.HttpServlet service()
HttpServlet.java line 820
in javax.servlet.http.HttpServlet service()
ServletHolder.java line 511
in org.mortbay.jetty.servlet.ServletHolder handle()
ServletHandler.java line 1221
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
UserAgentFilter.java line 78
in org.mortbay.servlet.UserAgentFilter doFilter()
GzipFilter.java line 131
in org.mortbay.servlet.GzipFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
JAMonServletFilter.java line 48
in com.jamonapi.http.JAMonServletFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
JavaMelodyFacade.java line 109
in com.cloudera.enterprise.JavaMelodyFacade$MonitoringFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
FilterChainProxy.java line 311
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
FilterSecurityInterceptor.java line 116
in org.springframework.security.web.access.intercept.FilterSecurityInterceptor invoke()
FilterSecurityInterceptor.java line 83
in org.springframework.security.web.access.intercept.FilterSecurityInterceptor doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
ExceptionTranslationFilter.java line 113
in org.springframework.security.web.access.ExceptionTranslationFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
SessionManagementFilter.java line 101
in org.springframework.security.web.session.SessionManagementFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
AnonymousAuthenticationFilter.java line 113
in org.springframework.security.web.authentication.AnonymousAuthenticationFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
RememberMeAuthenticationFilter.java line 146
in org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
SecurityContextHolderAwareRequestFilter.java line 54
in org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
RequestCacheAwareFilter.java line 45
in org.springframework.security.web.savedrequest.RequestCacheAwareFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
AbstractAuthenticationProcessingFilter.java line 182
in org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
LogoutFilter.java line 105
in org.springframework.security.web.authentication.logout.LogoutFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
SecurityContextPersistenceFilter.java line 87
in org.springframework.security.web.context.SecurityContextPersistenceFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
ConcurrentSessionFilter.java line 125
in org.springframework.security.web.session.ConcurrentSessionFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
FilterChainProxy.java line 173
in org.springframework.security.web.FilterChainProxy doFilter()
DelegatingFilterProxy.java line 237
in org.springframework.web.filter.DelegatingFilterProxy invokeDelegate()
DelegatingFilterProxy.java line 167
in org.springframework.web.filter.DelegatingFilterProxy doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
CharacterEncodingFilter.java line 88
in org.springframework.web.filter.CharacterEncodingFilter doFilterInternal()
OncePerRequestFilter.java line 76
in org.springframework.web.filter.OncePerRequestFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
ServletHandler.java line 399
in org.mortbay.jetty.servlet.ServletHandler handle()
SecurityHandler.java line 216
in org.mortbay.jetty.security.SecurityHandler handle()
SessionHandler.java line 182
in org.mortbay.jetty.servlet.SessionHandler handle()
SecurityHandler.java line 216
in org.mortbay.jetty.security.SecurityHandler handle()
ContextHandler.java line 766
in org.mortbay.jetty.handler.ContextHandler handle()
WebAppContext.java line 450
in org.mortbay.jetty.webapp.WebAppContext handle()
HandlerWrapper.java line 152
in org.mortbay.jetty.handler.HandlerWrapper handle()
StatisticsHandler.java line 53
in org.mortbay.jetty.handler.StatisticsHandler handle()
HandlerWrapper.java line 152
in org.mortbay.jetty.handler.HandlerWrapper handle()
Server.java line 326
in org.mortbay.jetty.Server handle()
HttpConnection.java line 542
in org.mortbay.jetty.HttpConnection handleRequest()
HttpConnection.java line 928
in org.mortbay.jetty.HttpConnection$RequestHandler headerComplete()
HttpParser.java line 549
in org.mortbay.jetty.HttpParser parseNext()
HttpParser.java line 212
in org.mortbay.jetty.HttpParser parseAvailable()
HttpConnection.java line 404
in org.mortbay.jetty.HttpConnection handle()
SelectChannelEndPoint.java line 410
in org.mortbay.io.nio.SelectChannelEndPoint run()
QueuedThreadPool.java line 582
in org.mortbay.thread.QueuedThreadPool$PoolThread run()

Caused by: org.postgresql.util.PSQLException:FATAL: password authentication failed for user "cloudera-scm"
at ConnectionFactoryImpl.java line 291
in org.postgresql.core.v3.ConnectionFactoryImpl doAuthentication()

Stack Trace:

ConnectionFactoryImpl.java line 291
in org.postgresql.core.v3.ConnectionFactoryImpl doAuthentication()
ConnectionFactoryImpl.java line 108
in org.postgresql.core.v3.ConnectionFactoryImpl openConnectionImpl()
ConnectionFactory.java line 66
in org.postgresql.core.ConnectionFactory openConnection()
AbstractJdbc2Connection.java line 125
in org.postgresql.jdbc2.AbstractJdbc2Connection <init>()
AbstractJdbc3Connection.java line 30
in org.postgresql.jdbc3.AbstractJdbc3Connection <init>()
AbstractJdbc3gConnection.java line 22
in org.postgresql.jdbc3g.AbstractJdbc3gConnection <init>()
AbstractJdbc4Connection.java line 30
in org.postgresql.jdbc4.AbstractJdbc4Connection <init>()
Jdbc4Connection.java line 24
in org.postgresql.jdbc4.Jdbc4Connection <init>()
Driver.java line 393
in org.postgresql.Driver makeConnection()
Driver.java line 267
in org.postgresql.Driver connect()
DriverManager.java line 571
in java.sql.DriverManager getConnection()
DriverManager.java line 215
in java.sql.DriverManager getConnection()
SqlRunner.java line 109
in com.cloudera.enterprise.dbutil.SqlRunner open()
SqlRunner.java line 80
in com.cloudera.enterprise.dbutil.SqlRunner runSingleQuery()
DbUtil.java line 679
in com.cloudera.enterprise.dbutil.DbUtil fetchEmbeddedDbUsers()
DbTestConnUtil.java line 340
in com.cloudera.server.web.cmf.DbTestConnUtil populateDbTestConnInfos()
AddRoleWizard.java line 244
in com.cloudera.server.web.cmf.wizard.service.AddRoleWizard getTestDatabaseData()
GenericAddRoleWizardController.java line 330
in com.cloudera.server.web.cmf.wizard.service.GenericAddRoleWizardController getDbSetupData()
<generated> line -1
in com.cloudera.server.web.cmf.wizard.service.GenericAddRoleWizardController$$FastClassByCGLIB$$3016baee invoke()
MethodProxy.java line 191
in net.sf.cglib.proxy.MethodProxy invoke()
Cglib2AopProxy.java line 688
in org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation invokeJoinpoint()
ReflectiveMethodInvocation.java line 150
in org.springframework.aop.framework.ReflectiveMethodInvocation proceed()
MethodSecurityInterceptor.java line 61
in org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor invoke()
ReflectiveMethodInvocation.java line 172
in org.springframework.aop.framework.ReflectiveMethodInvocation proceed()
Cglib2AopProxy.java line 621
in org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor intercept()
<generated> line -1
in com.cloudera.server.web.cmf.wizard.service.GenericAddRoleWizardController$$EnhancerByCGLIB$$69955bfd getDbSetupData()
NativeMethodAccessorImpl.java line -2
in sun.reflect.NativeMethodAccessorImpl invoke0()
NativeMethodAccessorImpl.java line 57
in sun.reflect.NativeMethodAccessorImpl invoke()
DelegatingMethodAccessorImpl.java line 43
in sun.reflect.DelegatingMethodAccessorImpl invoke()
Method.java line 606
in java.lang.reflect.Method invoke()
HandlerMethodInvoker.java line 176
in org.springframework.web.bind.annotation.support.HandlerMethodInvoker invokeHandlerMethod()
AnnotationMethodHandlerAdapter.java line 436
in org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter invokeHandlerMethod()
AnnotationMethodHandlerAdapter.java line 424
in org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter handle()
DispatcherServlet.java line 790
in org.springframework.web.servlet.DispatcherServlet doDispatch()
DispatcherServlet.java line 719
in org.springframework.web.servlet.DispatcherServlet doService()
FrameworkServlet.java line 669
in org.springframework.web.servlet.FrameworkServlet processRequest()
FrameworkServlet.java line 574
in org.springframework.web.servlet.FrameworkServlet doGet()
HttpServlet.java line 707
in javax.servlet.http.HttpServlet service()
HttpServlet.java line 820
in javax.servlet.http.HttpServlet service()
ServletHolder.java line 511
in org.mortbay.jetty.servlet.ServletHolder handle()
ServletHandler.java line 1221
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
UserAgentFilter.java line 78
in org.mortbay.servlet.UserAgentFilter doFilter()
GzipFilter.java line 131
in org.mortbay.servlet.GzipFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
JAMonServletFilter.java line 48
in com.jamonapi.http.JAMonServletFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
JavaMelodyFacade.java line 109
in com.cloudera.enterprise.JavaMelodyFacade$MonitoringFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
FilterChainProxy.java line 311
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
FilterSecurityInterceptor.java line 116
in org.springframework.security.web.access.intercept.FilterSecurityInterceptor invoke()
FilterSecurityInterceptor.java line 83
in org.springframework.security.web.access.intercept.FilterSecurityInterceptor doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
ExceptionTranslationFilter.java line 113
in org.springframework.security.web.access.ExceptionTranslationFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
SessionManagementFilter.java line 101
in org.springframework.security.web.session.SessionManagementFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
AnonymousAuthenticationFilter.java line 113
in org.springframework.security.web.authentication.AnonymousAuthenticationFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
RememberMeAuthenticationFilter.java line 146
in org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
SecurityContextHolderAwareRequestFilter.java line 54
in org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
RequestCacheAwareFilter.java line 45
in org.springframework.security.web.savedrequest.RequestCacheAwareFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
AbstractAuthenticationProcessingFilter.java line 182
in org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
LogoutFilter.java line 105
in org.springframework.security.web.authentication.logout.LogoutFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
SecurityContextPersistenceFilter.java line 87
in org.springframework.security.web.context.SecurityContextPersistenceFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
ConcurrentSessionFilter.java line 125
in org.springframework.security.web.session.ConcurrentSessionFilter doFilter()
FilterChainProxy.java line 323
in org.springframework.security.web.FilterChainProxy$VirtualFilterChain doFilter()
FilterChainProxy.java line 173
in org.springframework.security.web.FilterChainProxy doFilter()
DelegatingFilterProxy.java line 237
in org.springframework.web.filter.DelegatingFilterProxy invokeDelegate()
DelegatingFilterProxy.java line 167
in org.springframework.web.filter.DelegatingFilterProxy doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
CharacterEncodingFilter.java line 88
in org.springframework.web.filter.CharacterEncodingFilter doFilterInternal()
OncePerRequestFilter.java line 76
in org.springframework.web.filter.OncePerRequestFilter doFilter()
ServletHandler.java line 1212
in org.mortbay.jetty.servlet.ServletHandler$CachedChain doFilter()
ServletHandler.java line 399
in org.mortbay.jetty.servlet.ServletHandler handle()
SecurityHandler.java line 216
in org.mortbay.jetty.security.SecurityHandler handle()
SessionHandler.java line 182
in org.mortbay.jetty.servlet.SessionHandler handle()
SecurityHandler.java line 216
in org.mortbay.jetty.security.SecurityHandler handle()
ContextHandler.java line 766
in org.mortbay.jetty.handler.ContextHandler handle()
WebAppContext.java line 450
in org.mortbay.jetty.webapp.WebAppContext handle()
HandlerWrapper.java line 152
in org.mortbay.jetty.handler.HandlerWrapper handle()
StatisticsHandler.java line 53
in org.mortbay.jetty.handler.StatisticsHandler handle()
HandlerWrapper.java line 152
in org.mortbay.jetty.handler.HandlerWrapper handle()
Server.java line 326
in org.mortbay.jetty.Server handle()
HttpConnection.java line 542
in org.mortbay.jetty.HttpConnection handleRequest()
HttpConnection.java line 928
in org.mortbay.jetty.HttpConnection$RequestHandler headerComplete()
HttpParser.java line 549
in org.mortbay.jetty.HttpParser parseNext()
HttpParser.java line 212
in org.mortbay.jetty.HttpParser parseAvailable()
HttpConnection.java line 404
in org.mortbay.jetty.HttpConnection handle()
SelectChannelEndPoint.java line 410
in org.mortbay.io.nio.SelectChannelEndPoint run()
QueuedThreadPool.java line 582
in org.mortbay.thread.QueuedThreadPool$PoolThread run()

any response will greatly appricated,

-mugi-

Re: Error during add datanode service

Darren — Wed, 17 Dec 2014 19:40:25 GMT

It sounds like there's a problem connecting to the embedded db. Do you have the embedded postgresql database set up?

Does the password in /var/lib/cloudera-scm-server-db/data/generated_password.txt work for the cloudera-scm user? (psql -h localhost -U cloudera-scm -p 7432 )

Is your CM server still configured to use that database? (/etc/cloudera-scm-server/db.properties)

Does this file exist? /etc/cloudera-scm-server/db.mgmt.properties

Re: Error during add datanode service

i9um0 — Thu, 18 Dec 2014 03:41:52 GMT

Hi,

we still using postgresql CM DB and already check to etc/cloudera-scm-server/db.mgmt.properties all connection ok. All Cloudera manager management services running well and never any trouble, command "psql -h localhost -U cloudera-scm -p 7432" executed with no error it mean with we can connect using cloudera-scm to postgresql through psql.

regards,

-mugi-

Re: Error during add datanode service

Darren — Thu, 18 Dec 2014 04:02:42 GMT

That's pretty surprising, since the error message clearly said there was a problem logging in to postgresql as cloudera-scm, and CM will always use the password in /var/lib/cloudera-scm-server-db/data/generated_password.txt to connect to this account.

Just to confirm, you used the same password in /var/lib/cloudera-scm-server-db/data/generated_password.txt to log in, right?

Also, the format of that file should look like:

$PASSWORD

The password above was generated by $0 (part of the cloudera-manager-server-db package)
and is the password for the user 'cloudera-scm' for the database in the current directory.

Generated at $NOW.

If it was modified, like if something was added to the top of the file, that could cause an issue. I admit this is a long shot.

Re: Error during add datanode service

i9um0 — Thu, 18 Dec 2014 04:21:36 GMT

yes,

and the file format is same like you type here. Btw, i still curious with this error on our production cluster cause on our development cluster it's never happen whereas the CDH version of both cluster are same.

regards,

-mugi-

Re: Error during add datanode service

Darren — Thu, 18 Dec 2014 05:05:46 GMT

Sadly I'm out of theories as to why it isn't working as expected = /

It's worth noting that the embedded db is not recommended for production. In addition to the normal reasons for not using it (performance, manageability, etc), moving off of the embedded db will definitely make this error go away, as it wouldn't even invoke that code path.

You could also try renaming /etc/cloudera-scm-server/db.mgmt.properties so that CM no longer sees it, and restarting CM. This will probably disable the features around automatic database creation (ie you have to create the user and database manually, but CM will still create the tables for you), but will also probably avoid the bug you're seeing.

Re: Error during add datanode service

i9um0 — Thu, 18 Dec 2014 07:39:46 GMT

I must confirm to our hadoop admin which method that they us when installing cloudera manager. but our question what are the differences about the embedded database and the other ? is it just only separate machine or it can be install on same machine with enough capacity to cater the load.

regards,

-mugi-

Re: Error during add datanode service

Darren — Fri, 19 Dec 2014 05:43:53 GMT

The database can live on the same machine as CM. Having it separate generally makes it easier to tune and manage, which can be important in production.

As your cluster grows, it is helpful to split up the databases needed by various roles / services to different machines.

The database guide has relevant reading. If you click on the links to the individual database guides at the bottom (mysql, oracle, external postgres) you'll see some additional guidelines.
http://www.cloudera.com/content/cloudera/en/documentation/core/latest/topics/cm_ig_installing_configuring_dbs.html

Thanks,
Darren

Re: Error during add datanode service

i9um0 — Fri, 19 Dec 2014 06:11:14 GMT

Hi Darren,

thank's before for quick response. is there any guidance for sizing CM server and DB hardware spesification? we hava a plan to add more nodes in our production cluster.

regards,

-mugi-

Re: Error during add datanode service

Darren — Fri, 19 Dec 2014 19:34:47 GMT

Hi Mugi,

The docs I linked offer some guidance for things like max connections, which can help determine the sizing of your DB hardware.

Usually the DB load from CM and monitoring is not extreme, but for 20+ node clusters we recommend splitting all monitoring roles and databases to be on a separate host than CM server to spread the load. How many can be shared on a host depends on cluster size.

I'm frankly not an expert in this area, but others may be able to chime in. You can also of course get official support for your cluster and get reliable access to this kind of expertise (</shameless plug>).

Thanks,
Darren