McDATA Eclipse 2640 SAN, Administration And Configuration Manual

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Eclipse™ 2640 SAN Router Administration and Configuration Manual
Configuring TCP Ports for iFCP
Select Hardware Compression from the Compression Level
drop-down list. This has the lowest compression ratio, but it
can run at link rate.
3. Select
Selective ACKnowledgement
(SACK) to acknowledge
non-contiguous sequence numbers. This reduces the amount of
retransmitted data when packets are lost. Enabling this provides
better performance in congested networks (assuming the remote
device also supports SACK).
Setting FastWrite Features
1. Select the
FastWrite
feature to improve performance for distance
over 200 Km. The FastWrite feature can minimize the data
transfer delay for write operations on long distance links by
responding to
Initiator Write
commands with
TransferReadys
. This
fills the WAN pipes and buffers the data at the SAN Router that is
closest to the target. The SAN Router that is buffering the data
then feeds it to the actual target at the rate that the target can
handle. Therefore, FastWrite makes up for the round-trip delays
typical of most WAN links. Note that FastWrite does not spoof
Write Status commands, thus ensuring data integrity.
NOTE:
Port reset is not required when changing FastWrite options in the
TCP Advanced Options dialog box
When the FastWrite is enabled, several additional parameters are
available to customize the FastWrite behavior:
• XFER_RDY Limit: The maximum number of XFER_RDY
commands that may be issued early by the SAN Router to
avoid round trip delays. The limit is applied to each Fabric
Channel login session.
• XFER_RDY Windowing: When selected, the configurable
XFER_RDY limit is treated as a moving “window” of
consecutive XFER_RDYs that may be issued by the early
SAN router. If not selected, the XFER_RDY limit is simply
the total number of XFER_RDY commands that can be
simultaneously outstanding for each login session.
• Remote Buffer Management: When selected, the local SAN
Router limits the amount of buffer memory used in the
remote SAN Router by limiting the amount of data
requested by the local SAN Router and sent to remote SAN