合 Oracle scmn进程占用CPU或内存很高
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目录
现象
在19c的rac中，有一个节点内存很高，top结果：
1 2 3 4 5 6 | 5937 oracle 20 0 163.3g 125.1g 125.0g S 3.6 49.7 263:09.55 ora_scmn_orcl1 5939 oracle 20 0 163.3g 124.9g 124.9g S 4.0 49.6 249:26.99 ora_scmn_orcl1 5935 oracle 20 0 163.3g 124.9g 124.9g S 3.3 49.6 250:00.64 ora_scmn_orcl1 5941 oracle 20 0 163.3g 124.9g 124.9g S 5.0 49.6 262:19.10 ora_scmn_orcl1 5966 oracle 20 0 163.0g 120.2g 120.2g S 1.7 47.8 86:58.62 ora_dbw0_orcl1 5971 oracle 20 0 161.0g 119.8g 119.8g S 2.6 47.6 86:49.51 ora_dbw2_orcl1 |
配置
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | cat >> /etc/sysctl.conf <<"EOF" vm.swappiness = 10 vm.dirty_background_ratio = 3 vm.dirty_ratio = 80 vm.dirty_expire_centisecs = 500 vm.dirty_writeback_centisecs = 100 vm.min_free_kbytes = 6097152 kernel.shmmni = 4096 kernel.shmall = 1073741824 kernel.shmmax = 4398046511104 kernel.sem = 1024 60000 1024 256 net.ipv4.ip_local_port_range = 9000 65500 net.core.rmem_default = 262144 net.core.rmem_max = 4194304 net.core.wmem_default = 262144 net.core.wmem_max = 1048576 fs.aio-max-nr = 1048576 fs.file-max = 6815744 kernel.panic_on_oops = 1 kernel.watchdog_thresh=30 EOF /sbin/sysctl -p |
High SYS CPU Usage ON LMS Thread (SCMN/CR00/RS01) During High Workload (Doc ID 2707048.1)
SYMPTOMS
ON 6-node 19.5 RAC On Red Hat Enterprise 7, it's observed that high SYS CPU is utilized by lms/scmn process/thread during high workload. for example, the issue can be reproduces by below test:
Start parallel recovery(as it is a standby DB).
At the same time, execute a full database backup using rman on the standby.
The issue not only happens on standby, it can also happen on primary or any other RAC environments during high workload.
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