MySQL TroubleShoting: no operation, full disk I/O Load

MySQL TroubleShoting: no operation, disk I/O load full (I) Environment: OS: RHEL-5.8 Server: MySQL 5.5 Engine: InnoDB (ii) Problem: without any operation, the disk I/O load is almost full, and after 3 or 4 hours, the DISK load is still iotop part. Output: [plain] Total DISK READ: 32.55 M/s | Total disk write: 0.00 B/s tid prio user disk read disk write swapin io> COMMAND 535 be/4 mysql 3.26 M/s 0.00 B/s 0.00% 80.88% mysqld -- basedir =... 536 be/4 mysql 29.26 M/s 0.00 B/s 0.00% 71.93% mysqld -- basedir = ......... (iii) symptom: perform a full update Performance Test on sysbench and shut down the database after the test is completed. However, this problem is found after restart, and the problem persists after 3 or 4 hours. (4) cause: [plain] ① innodb_fast_shutdown => 1: when the switch buffer is disabled, the merge and purge operations of the change buffer are not performed, but the innodb_fast_shutdown => 0 is performed in the next boot cycle: the merge change buffer and purge operations are performed when the database is closed.