Excessive LAG on OGG extract Data Pump Sending Data Over WAN, calculate TCP TCPBUFSIZE TCPFLUSHBYTES [ID 1071892.1]

Version 10.4.0.12 and later

症狀：

datapump程式嚴重lag，並未達到預期的網路吞吐量

誘因：

OGG的tcpbufsize預設30000位元組，對繁忙網路設定過小；

系統沒有啟用tcp window scale；

系統的socket buffer過小；

診斷：

先透過ping檢視RTT，並計算實際吞吐量；

開啟tcp window scale；

提升socket buffer；

$ ping -s target 56 4

PING target: 56 data bytes

64 bytes from target.mydomain.com (10.221.65.15): icmp_seq=0. time=39. ms

64 bytes from target.mydomain.com (10.221.65.15): icmp_seq=1. time=39. ms

64 bytes from target.mydomain.com (10.221.65.15): icmp_seq=2. time=39. ms

64 bytes from target.mydomain.com (10.221.65.15): icmp_seq=3. time=39. ms

----redsap58 PING Statistics----

4 packets transmitted, 4 packets received, 0% packet loss

round-trip (ms) min/avg/max = 39/39/39

由上可得rtt=39ms，假定頻寬為155Mbps，網路吞吐量=min(155M,socket_buffer/rtt)，則socket_buffer=155M*rtt/8=755625 bytes

將tcpbufsize/tcpflushbytes設定為755625

RMTHOST target, MGRPORT 7809, TCPBUFSIZE 755625, TCPFLUSHBYTES 755625；

開啟tcp scale window;

增大socket buffer

net.core.rmem_max

net.core.wmem_max

net.ipv4.tcp_rmem

net.ipv4.tcp_wmem

net.ipv4.tcp_window_scaling

具體可參照

http://space.itpub.net/15480802/viewspace-757720

goldengate的datapump調優

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