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large buffer can improve communication performance, but requires more
memory.
TCPWINDOWSIZE
The TCPWINDOWSIZE option specifies the size of the TCP/IP sliding window in
kilobytes. This option overrides the operating system's TCP send and receive
spaces. It specifies the size of the TCP sliding window for all clients, and all but
MVS servers. A larger window size can improve communication performance,
but uses more memory. It enables multiple frames to be sent before an
acknowledgment is obtained from the receiver. If long transmission delays are
being observed, increasing the TCPWINDOWSIZE may improve throughput.
TCPNODELAY
The TCPNODELAY option, when set to Yes, allows data packets less than the
yes
MTU size to be sent out immediately. We recommend setting the value to
.
15.4.3 General parameters
These parameters can affect system performance and can be manually tuned
according to client requirements.
COMPRESSION
The COMPRESSION option compresses files before they are sent to the Tivoli
Storage Manager server. Compressing files reduces the amount of data storage
required to store backup versions and archive copies of your files. It can,
however, affect Tivoli Storage Manager throughput because of the CPU cycles
required to compress the file.
Client data compression will save storage space, network capacity, and server
cycles. However, compression may decrease throughput. If compression is on,
backups can be significantly slower, depending on client processor speed, than if
it were disabled. Compression may be beneficial for a fast processor on a slow
network, but probably not for a slow processor on a fast network.
By default, files continue compressing even if the operation is causing the file
size to increase. This can be the case if you are backing up already compressed
files, such as ZIP archives. To prevent continued compression if the file size
grows, and to send the file again without compression, use the
no
COMPRESSALWAYS option set to
. When set to no, the current transaction
will get rolled back and the objects for the transactions need to get retransmitted.
You might want to edit your include/exclude list to exclude precompressed
options from compression using the exclude.compression option.
509
Chapter 15. Performance considerations
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