使用pg_basebackup 创建流复制备库时，需要复制并传送数据，带来大量 I/O，9.4 版本 pg_basebackup 增加流量控制选项，搭建流复制备库时降低对主库的性能影响。
关于 –max-rate 选项
指数据的最大传输速率，默认是 kb/s 为单位，也可以是 Mb/s, 允许的值范围是 32K 到 1024 Mb，超出这个范围为报以下错误。
超出速率范围
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[pg94@db2 pg94]$ pg_basebackup -D /database/pg94/pg_root -Fp -Xs -v -P -h 192.168.2.37 -p 1924 -U repuser
pg_basebackup: transfer rate "2" is out of range
[pg94@db2 pg94]$ pg_basebackup -D /database/pg94/pg_root -Fp -Xs -v -P -h 192.168.2.37 -p 1924 -U repuser
pg_basebackup: transfer rate "1025M" is out of range
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设置最大传输速率 64 KB/s
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[pg94@db2 pg94]$ pg_basebackup -D /database/pg94/pg_root -Fp -Xs -v -P -h 192.168.2.37 -p 1924 -U repuser --max-rate=64
transaction log start point: 0/50000058 on timeline 1
pg_basebackup: starting background WAL receiver
10145/1449790 kB (0%), 0/2 tablespaces (...ncs/PG_9.4_201405111/16386/16587)
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查看网卡流量
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[root@db2 ~]# sar -n DEV 1 1000
02:39:22 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s
02:39:23 PM lo 0.00 0.00 0.00 0.00 0.00 0.00 0.00
02:39:23 PM eth0 50.00 41.00 66.65 2.61 0.00 0.00 0.00
02:39:23 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s
02:39:24 PM lo0.00 0.00 0.00 0.00 0.00 0.00 0.00
02:39:24 PM eth0 56.57 48.48 75.72 3.01 0.00 0.00 0.00
02:39:24 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s
02:39:25 PM lo0.00 0.00 0.00 0.00 0.00 0.00 0.00
02:39:25 PM eth0 50.51 47.47 67.32 2.95 0.00 0.00 0.00
02:39:25 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s
02:39:26 PM lo0.00 0.00 0.00 0.00 0.00 0.00 0.00
02:39:26 PM eth0 51.52 35.35 67.41 2.31 0.00 0.00 0.00
02:39:26 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s
02:39:27 PM lo0.00 0.00 0.00 0.00 0.00 0.00 0.00
02:39:27 PM eth0 56.00 31.00 74.96 2.08 0.00 0.00 0.00
02:39:27 PM IFACE rxpck/s txpck/s rxkB/s txkB/s rxcmp/s txcmp/s rxmcst/s
02:39:28 PM lo0.00 0.00 0.00 0.00 0.00 0.00 0.00
02:39:28 PM eth0 56.57 48.48 75.72 3.01 0.00 0.00 0.00
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参考
原创文章，作者：306829225，如若转载，请注明出处：https://blog.ytso.com/238069.html
