PC Gen: Using the DEC Redirector Slows Mail
ID: Q131914
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The information in this article applies to:
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Microsoft Mail for PC Networks, versions 3.2, 3.2a
SYMPTOMS
When you use the DEC redirector to connect to a Pathworks server that has
the version 3.2 or 3.2a Microsoft Mail for PC Networks database, and the
mail message file (MMF) is stored on the server, Microsoft Mail for Windows
runs extremely slowly when you send or receive messages.
CAUSE
Mail accesses the MMF by using byte range locking, so to send or receive a
message, it attempts to lock a byte range on the MMF, even if it already
has a lock on that byte range. The Pathworks server handles multiple byte
range locks on the same range as a file lock violation, even when the lock
comes from the same workstation. When the server rejects the lock, the
redirector attempts three more times to establish the lock, and succeeds on
the last attempt. This creates a delay while Mail waits for the redirector
to establish the lock.
The Pathworks server also adds to the delay by increasing the response
delay when multiple file lock violations occurs on a file. Between the
redirector trying four times and the server waiting longer and longer
between these attempts to respond to the workstation, Mail effectively
stops running for 4 to 10 seconds per message.
RESOLUTION
This is not a problem with Mail but with the underlying network
architecture.
The resolution can be one of the following:
- Move the MMF files to the local workstation.
- Upgrade the Pathworks server to version 5.0, and use the DEC
redirector version 5.0 in enhanced mode.
- Upgrade Microsoft Windows version 3.1 to Microsoft Windows for
Workgroups 3.11, and use the enhanced redirector.
MORE INFORMATION
Testing shows that the problem occurs primarily when you use Pathworks
version 4.1, the DEC redirector version 4.1a, and Windows version 3.1; it
can also occur when you run the DEC redirector version 5.0 in basic mode.
The following table summarizes the results of testing:
Client OS Redir Mode Server Result
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Windows 3.1 4.1a basic 4.1 failed (1)
Windows 3.1 4.1a enhanced 4.1 failed (1)
Windows for Workgroups 3.11 4.1a enhanced 4.1 OK (2)
Windows 3.1 4.1a enhanced NTAS 3.5 OK (3)
Windows 3.1 5.0 enhanced 4.1 failed (1)
Windows 3.1 5.0 basic 5.0 failed (1)
Windows 3.1 5.0 enhanced 5.0 OK (4)
Windows for Workgroups 3.11 5.1 enhanced 5.0 OK (5)
Windows for Workgroups 3.11 5.1 enhanced 5.0 OK (5)
Notes:
- (1) 4 lock violations per message
- (2) file lock broken and file relocked, no violation
- (3) 1 lock violation.
- (4) 1 lock violation. Response from server was slow (~520 ms).
- (5) No file locks were made
Additional query words:
3.20 slow
Keywords :
Version : WINDOWS:3.2,3.2a
Platform : WINDOWS
Issue type :