LVM2中Snapshot对LVM读写性能影响

川长思鸟来 2022-06-06 22:53 214阅读 0赞

# 操作环境 #

Centos 7

Mysql 5.7

sysbench 0.4.12

# 操作说明 #

LVM2中snapshot使用的COW方式进行快照，在写数据的时候会对写性能有影响。

通过sysbench对mysql进行性能测试，了解性能影响的程度。

# 操作步骤 #

1.通过sysbench测试未启动snapshot时mysql的性能

准备mysql数据

[root@centos7-mysql ~]# sysbench --test=oltp --oltp-table-size=10000000 --db-driver=mysql --mysql-socket=/usr/local/mysql/mysql.sock --mysql-user=root --mysql-password='123456' --mysql-db=sbtest prepare

开始测试

[root@centos7-mysql ~]# sysbench --test=oltp --oltp-table-size=10000000 --oltp-read-only=off --init-rng=on --num-threads=16 --max-requests=0 --oltp-dist-type=uniform --max-time=600 --mysql-user=root --mysql-password='123456' --db-driver=mysql --mysql-socket=/usr/local/mysql/mysql.sock run > result-nosnap.log

2.给lv创建快照

[root@centos7-mysql ~]# lvcreate -s -n snapdatalv-1 -L 10G /dev/vgtest/datalv

[root@centos7-mysql ~]# lvs
      LV           VG     Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
      root         centos -wi-ao---- <13.91g                                                    
      swap         centos -wi-ao----   1.60g                                                    
      datalv       vgtest owi-aos---  20.00g                                                    
      snapdatalv-1 vgtest swi-a-s---  10.00g      datalv  0.01

3.通过sysbench测试启动snapshot时mysql的性能

[root@centos7-mysql ~]# sysbench --test=oltp --oltp-table-size=10000000 --oltp-read-only=off --init-rng=on --num-threads=16 --max-requests=0 --oltp-dist-type=uniform --max-time=600 --mysql-user=root --mysql-password='hgctech' --db-driver=mysql --mysql-socket=/usr/local/mysql/mysql.sock run > result-withsnap.log

4.对比两者的性能

未启动snapshot时，mysql性能

[root@centos7-mysql ~]# cat result-nosnap.log 
    sysbench 0.4.12:  multi-threaded system evaluation benchmark
    
    Running the test with following options:
    Number of threads: 16
    Initializing random number generator from timer.
    
    
    Doing OLTP test.
    Running mixed OLTP test
    Using Uniform distribution
    Using "BEGIN" for starting transactions
    Using auto_inc on the id column
    Threads started!
    Time limit exceeded, exiting...
    (last message repeated 15 times)
    Done.
    
    OLTP test statistics:
        queries performed:
            read:                            674240
            write:                           240800
            other:                           96320
            total:                           1011360
        transactions:                        48160  (80.23 per sec.)
        deadlocks:                           0      (0.00 per sec.)
        read/write requests:                 915040 (1524.42 per sec.)
        other operations:                    96320  (160.47 per sec.)
    
    Test execution summary:
        total time:                          600.2526s
        total number of events:              48160
        total time taken by event execution: 9602.5361
        per-request statistics:
             min:                                  4.80ms
             avg:                                199.39ms
             max:                               3170.00ms
             approx.  95 percentile:             384.15ms
    
    Threads fairness:
        events (avg/stddev):           3010.0000/22.35
        execution time (avg/stddev):   600.1585/0.06

启动snapshot时，mysql的性能

[root@centos7-mysql ~]# cat result-withsnap.log 
    sysbench 0.4.12:  multi-threaded system evaluation benchmark
    
    Running the test with following options:
    Number of threads: 16
    Initializing random number generator from timer.
    
    
    Doing OLTP test.
    Running mixed OLTP test
    Using Uniform distribution
    Using "BEGIN" for starting transactions
    Using auto_inc on the id column
    Threads started!
    Time limit exceeded, exiting...
    (last message repeated 15 times)
    Done.
    
    OLTP test statistics:
        queries performed:
            read:                            294938
            write:                           105335
            other:                           42134
            total:                           442407
        transactions:                        21067  (35.09 per sec.)
        deadlocks:                           0      (0.00 per sec.)
        read/write requests:                 400273 (666.70 per sec.)
        other operations:                    42134  (70.18 per sec.)
    
    Test execution summary:
        total time:                          600.3788s
        total number of events:              21067
        total time taken by event execution: 9602.5025
        per-request statistics:
             min:                                  5.17ms
             avg:                                455.81ms
             max:                               5379.73ms
             approx.  95 percentile:            1065.17ms
    
    Threads fairness:
        events (avg/stddev):           1316.6875/25.72
        execution time (avg/stddev):   600.1564/0.10

![Image 1][] ![Center][]

通过上图对比，未启动snapshot时的性能远远高于启动snapshot时的性能。

[Image 1]: 
[Center]: /images/20220607/73472d7a03fd49c898f1ca563c8d3460.png