IBM Support

Setting TCPNODELAY in AIX

Question & Answer


Question

Tivoli Storage Manager by default sets TCPNODELAY to YES for both the server and the client. Is there a corresponding setting for the AIX OS?

Cause

Slow restore performance was seen from an AIX client while other Linux/Windows nodes performance were as expected. The environment where this issue occurred had an AIX 5.3 TSM 6.1.2.0 server and a Client of AIX 5.2 and TSM 6.1.0.0

Answer

AIX has a tcpnodelay setting which should also be checked or set to use tcpnodelay. The AIX command to use/set tcpnodelay on the OS resolved the restore performance problem on the client side. The command used is as follows:
no –p –o tcp_nodelayack=1

It is recommended the AIX Administrator review the above command and determine the impact on the business environment before proceeding.

Note: Per the Tivoli Storage Manager Server and Client manuals regarding TCPNODELAY:

    Change the value from the default of YES only under one of these conditions:
    - You are directed to change the option by your service representative.
    - You fully understand the effects of the TCP Nagle algorithm on network transmissions. Setting the option to NO enables the Nagle algorithm, which delays sending small successive packets.
Note: Issuing the AIX command "no -a" will provide a list of network options/settings. From this list the tcp_nodelayack can be determined.
    Example:
    > no -a
    arpqsize = 12
    arpt_killc = 20
    arptab_bsiz = 7
    arptab_nb = 149
    bcastping = 0
    ...
    tcp_nodelayack = 0
    ...

[{"Product":{"code":"SSGSG7","label":"Tivoli Storage Manager"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Component":"Client","Platform":[{"code":"PF002","label":"AIX"}],"Version":"All Supported Versions","Edition":"","Line of Business":{"code":"LOB26","label":"Storage"}}]

Product Synonym

TSM ADSM ITSM IBM Spectrum Protect

Document Information

Modified date:
17 June 2018

UID

swg21449348

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