Connection Count

(Only available in Exchange 2013)

Definition:
Is the total number of client connections maintained.

Information:
This is used to determine current load of the server's Information Store.

Possible problems:
May cause memory bottlenecks on the server if the number is excessively high.

Remediation:
Reduce the number of user mailboxes hosted on the server or increase available resources.

N/A

Active User Count

Definition:
Number of user connections that have shown some activity in the last 2 minutes.

Information:
Used to determine current user load on the server. Each active user typically starts up to 5 active sessions (connections) on a server, to sync various services.

Possible problems:
May cause memory bottlenecks on the server if the number is excessively high.

Remediation:
Determine if users are running applications not required for business use, and request they do not run these applications which is causing an increase in server logons. If this does not help, or is not possible, reduce the number of users hosted on the server and move any Public Folders on the server to a different server.

N/A

RPC Averaged Latency

Definition:
Indicates the RPC latency, in ms, averaged for all operations in the last 1,024 packets.

Information:
For information about how clients are affected when overall server RPC averaged latencies increase, see “Understanding Client Throttling Policies” at http://technet.microsoft.com/en-us/library/dd297964.aspx. Should not be higher than 100 ms on average.

Possible problems:
To determine if certain protocols are causing overall RPC latencies, monitor MSExchangeIS Client (*)\RPC Average Latency to separate latencies based on client protocol.

Remediation:
Faster disks, more disks, or redesigning existing disk arrays.

> 100 ms

RPC Requests

Definition:
Indicates the overall RPC requests currently executing within the information store process.

Information:
Should be below 70 at all times.

Possible problems:
When I/O counters fall outside of normal range, client performance is directly impacted. For example, Outlook and Outlook Web App (OWA) users report “Outlook is slow” when opening mail or moving between folders.

Remediation:
Faster disks, more disks, or redesigning existing disk arrays.

> 70

Active Connection Count

(Only available in Exchange 2010)

Definition:
Number of connections that have shown some activity in the last 10 minutes.

Information:
This is used to determine current load of the server's Information Store.

Possible problems:
May cause memory bottlenecks on the server if the number is excessively high.

Remediation:
Reduce the number of user mailboxes hosted on the server or increase available resources.

N/A

Client: RPCs Failed: Server too busy/sec

(Only available in Exchange 2010 and 2016)

Definition:
Shows the client-reported rate of failed RPCs (since the store was started) due to the Server Too Busy ROC error.

Information:
Should be 0 at all times.

Possible problems:
Higher values may indicate RPC threads are exhausted or client throttling is occurring for clients running versions of Outlook earlier than Microsoft Office Outlook 2007. This can cause user mail clients experiencing slowness.

Remediation:
Check if RPC latencies are high and determine the cause of the performance issue (e.g. poorly performing disk I/O, excessive load, insufficient memory, high number of users).

> 0 for 5 polls

RPC Client Backoff/sec

(Only available in Exchange 2010 and 2016)

Definition:
The rate at which the server notifies a client to withdraw (backoff).

Information:
Indicates the rate at which client backoffs are occurring.

Possible problems:
Higher values may indicate that the server may be incurring a higher load resulting in an increase in overall averaged RPC latencies, causing client throttling to occur. This can also occur when certain client user actions are being performed. Depending on what the client is doing and the rate at which RPC operations are occurring, it may be normal to see backoffs occurring.

Remediation:
Check if RPC latencies are high and determine the cause of the performance issue (e.g. poorly performing disk I/O, excessive load, insufficient memory, high number of users).

N/A

Active Client Logons

(Only available in Exchange 2010 and 2016)

Definition:
Number of logons that were active (issued any MAPI requests) within the last 10 minute time interval.

Information:
Active client logons can be high if users are logging on and logging off frequently.

Possible problems:
May cause memory bottlenecks on the server if the number is excessively high.

Remediation:
Determine if users are running applications not required for business use, and request they do not run these applications which is causing an increase in server logons. If this does not help, or is not possible, reduce the number of server hosted on the server and move any Public Folders on the server to a different server.

N/A

Messages Queued for Submission

(Only available in Exchange 2010 and 2016)

Definition:
Shows the current number of submitted messages not yet processed by the transport layer.

Information:
The queues should remain below 50 at any given time. Anything above this amount should be cleared within 15 minutes.

Possible problems:
Mailbox server is not communicating properly with the transport server.

Remediation:
Verify network connectivity and transport server functionality.

> 50

Slow FindRow Rate

(Only available in Exchange 2010 and 2016)

Definition:
Shows the rate at which the slower FindRow needs to be used in the mailbox store.

Information:
Should be no more than 10 for any specific mailbox store.

Possible problems:
Higher values indicate applications are crawling or searching mailboxes, which is affecting server performance. These include desktop search engines, customer relationship management (CRM), or other third-party applications.

Remediation:
Run the ResetSearchIndex.ps1 script which is located in the scripts directory at the root of the Exchange installation. Alternatively, you can perform the process manually:

1. Rebuild the index catalog using: Update-MailboxDatabaseCopy <DBName> -CatalogOnly command.
2. Stop the Microsoft Exchange Search Service.
3. Delete old catalog files.
4. Restart Microsoft Exchange Search Service.

N/A