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MCSE Help : 70-081 - Implementing and supporting  Microsoft Exchange Server 5.5 pt 3
Richard Adams takes us through the third and final part of exam number 70-081 – Implementing and Supporting Exchange Server 5.5
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The Monitoring & Optimisation Section

What to Revise : Monitoring Resources, Optimising Server Performance, Optimising Network Performance, Using Performance Optimizer.

Watch For:

  1. Monitoring Resources
  2. There are three basic resources of a server to monitor for performance – processor, disk and memory. Of these, processor is the least likely to be the problem and as such you should only consider upgrading the processor if there are no other bottlenecks caused by disk or memory. To monitor server performance use Performance Monitor from the Administrative Tools menu. Some of the common objects and counters to monitor for server performance are outlined below:

    Processor

    % Processor Time is used to determine how "busy" your processor is. A value consistently over 80% may indicate a processing bottleneck.

    Interrupts/Sec
    is used to determine how much time the processor spends dealing with hardware requests. A high value may indicate hardware driver problems.

    Memory

    Pages/Sec is used to determine the total amount of paging to and from RAM. A high value may indicate that more RAM is required.

    Page Reads/Sec
    and Page Writes/Sec are used to breakdown the total paging into what is going into RAM and what is coming out. If your system always has to page out prior to paging in this indicates a bottleneck.

    Physical or Logical Disk

    The hard disk is divided into Physical Disk and Logical Disk. Use logical disk to determine problems with specific volumes. Use physical disk to determine problems with disk drives. The counters must be "turned on" before they are available, due to the extra system overhead involved. To turn the disk counters on type DISKPERF –Y from the command prompt (or –YE for RAID arrays) and restart your computer. To turn the counters off type DISKPERF –N and again restart your computer.

    %Disk Time
    is the amount of time that the hard disk or volume is busy. A high percentage may indicate that your hard disk is a bottleneck.

    When Exchange Server 5.5 is installed, a new, extended set of objects and counters is added to the Performance Monitor application. These Exchange-specific objects allow you to constantly monitor the individual components of an Exchange Server – MTA, Private Information Store, Public Information Store, Directory Replication Connectors and Messaging Connectors.

  3. Optimising Server Performance

The recommended configuration for optimising the performance of an Exchange Server is to place the transaction log files on the fastest physical disk and have the disk dedicated just to this purpose. This will ensure the fastest write operation. To include fault tolerance, create a mirror of the partition on another disk (RAID 1). Then, create a stripe set for the database files. This will ensure the fastest read operation. Again, you can build-in fault tolerance, this time by making it a stripe set with parity (RAID 5).

To manually move files to optimum locations you should take the following steps:

  1. Stop the Exchange Server services (from Control Panel, Services).
  2. Take a backup of all files in case of accidents.
  3. Physically move the files to their new locations (using Windows Explorer).
  4. In Exchange Administrator select the File Locations tab of the properties of the server object and update the paths to the transaction logs and database files as necessary.
  5. Start the Exchange Server services (from Control Panel, Services).

Performance Optimiser can be used to assist with these procedures and is covered in a separate section.

  1. Optimising Network Performance

Network performance is especially important when there are multiple servers within a site and/or when there are multiple sites within an organisation. To optimise performance of Exchange Server data transfers over a poor quality network, adjust the messaging defaults values that are found on the MTA Site Configuration properties sheet from Exchange Administrator. The parameters and an explanation for each are given below:

RTS (Reliable Transfer Service)

Name Explanation
Checkpoint Size The amount of data (in k) transferred before inserting a checkpoint. This amount of data will be re-transferred in the event of an error. For reliable networks increase the checkpoint size to reduce overhead. For unreliable networks increase the checkpoint size to reduce overall transfer sizes.
Recovery Timeout The amount of time (in seconds) that is waited after an error for a reconnection before starting the transmission again from the beginning.
Window Size The amount of time (in seconds) that is waited after an error for a reconnection before starting the transmission again from the beginning.
Window Size The number of checkpoints to be sent before acknowledgements are received for the previously transmitted data. If you have a slow network, increase the number to prevent early suspension of data transfer.

Connection Retry Values

Name Explanation
Max Open Retries The total number of times a transmission is attempted. Decrease on a reliable network where the problem is likely to be other things.
Max Transfer Retries The maximum number of times a re-transmission over any one open connection is attempted. Increase for an unreliable network with intermittent problems
Open Interval The time (in seconds) waited before re-opening a failed connection. Set this appropriate to the pattern of errors on your network.
Transfer Interval The time (in seconds) waited before re-transmitting on a connection. Set this appropriate to the pattern of errors on your network.

Association Parameters

Name Explanation
Lifetime Time (in seconds) that a connection is left open for re-use. Reduce on a very busy network or if you commonly do not transmit many messages between the same servers.
Disconnect Time (in seconds) that a connection is left open for re-use even after a disconnect message is received from the other server. Reduce on a very busy network or if you commonly do not transmit many messages between the same servers.
Threshold The number of messages queued for any one association. For maximum speed of transfer reduce the threshold. To prevent overburdening of a busy network increase the threshold.

Transfer Timeouts

Name Explanation
Urgent The time for an urgent message (in seconds per k of message size) that the message is given to reach its destination before the attempt is given up and an NDR message is sent.
Normal The time for a normal message (in seconds per k of message size) that the message is given to reach its destination before the attempt is given up and an NDR message is sent.
Non-Urgent The time for a non-urgent message (in seconds per k of message size) that the message is given to reach its destination before the attempt is given up and an NDR message is sent.


4. Using Performance Optimizer

Performance Optimizer is the utility which is installed automatically in a default installation of Exchange Server to help gain the maximum performance from the server. The administrator is automatically prompted to run Performance Optimizer after an installation and should also run Performance Optimizer after a change in hardware (processor, disks or memory) or usage (change in numbers of mailboxes, public folders, site connectivity or replication). Performance Optimizer can be run from the Exchange Server menu or alternatively from a command line. The location and file name is c:\exchsrvr\bin\perfwiz.exe and the /v option can be used for verbose mode, allowing the administrator to override adjustments otherwise made automatically by the utility.

Performance Optimizer will automatically adjust placement of essentials files and configuration of memory. In order to do this you will be asked to supply the number of mailboxes on this server, the number of mailboxes in total for the organisation and each role of this server within the organisation – whether it contains mailboxes, public folders, replication connectors, etc.

The Troubleshooting Section

What to Revise

MSMail Synchronisation, DNS Configuration, Preventing Denial of Service Attacks, POP3 Mailbox Access, Internet Message Formats, RPC Binding Order.

Watch For:

  1. MSMail Synchronisation
  2. If you are implementing Exchange Server 5.5 alongside an existing MSMail post office and you wish to synchronise directories, remember that an MSMail group will not be able to span users from more than one post office (and your Exchange Server will also be seen as a separate post office). Exchange DLs (Distribution Lists) do not have this limitation.

  3. DNS Configuration
  4. The most likely cause of problems in sending messages using SMTP over the Internet or an intranet is incorrect configuration of DNS. DNS must be configured with at least one MX record for each domain. The MX record specifies the name of the server that contains the incoming Internet Mail Service. This record in turn must have a corresponding HOST record to be able to resolve the host’s IP address.

  5. Preventing Denial of Service Attacks
  6. The following are the most common ways of preventing DOS (Denial of Service) attacks on your mail service from the Internet: Installing and configuring a firewall, disabling automatic replies on the Internet, disabling out of office responses on the Internet and setting message size limits on the Internet Mail Service itself.

  7. POP3 Mailbox Access
  8. A user who accesses their messages stored on the Exchange Server both from the office using MAPI and from home using POP3 over the Internet must remember that any messages that he or she saves into private folders will not be visible from home, since POP3 is limited to only viewing the contents of the mailbox itself and not private (or public) folders. To overcome this limitation you could allow the user to use IMAP4 instead of POP3 to retrieve their mail from home.

  9. Internet Message Formats

If a user wishes to send mail via the Internet or intranet to Unix users via the Internet Mail Service then you must configure the Internet Mail Service to format messages destined to the domains where the Unix users are using UUEncode instead of MIME. You can do this from the Internet Mail page of the properties sheet for the Internet Mail Service object in Exchange Administrator.