????
Virtual Memory

??????????????棬??????????????????棬?????????????????????????????(SWAP)?????????????????(Virtual Memory)???????????????????????????????????????????????????????????????SWAP???д??????????????棬????????????swap???????????????????????????????汻????(x86????????С?4k)??????д?????????????λ?????????????????????????????????????????????????洢???????SWAP????????????swap??????????????????????潻??(Paging)??
???????????(free memory)?????????????????vmstat???free?????????????С?????????????????Ч?????????????е?????free???????Χ?????????????????20%?????????????С??????????80%??????????????????????????????????????????潻????????ж????????????????????潻????????????????????????????????????????????
??????潻??(Paging)????潻????????SWAP?????????????潻????SWAP??????????????????潻???????????????????vmstat??si??so?????
????· si??????SWAP??????????????С
????· so?????????д??SWAP???????С
????SWAP??????:?????vmstat??swpd????????SWAP??????????????ú???潻????????????????統swpd???0????si??so?????????0?????????????г???????????
??????. Disk
???????????????????????????????????????????????SSD?????д???????涼????????????????????????CPU????????????????????IO??????IO?????IO??????????????????????????????????????????????
???????IO???????д???????д???????ζ?д??????????С????IO??????????????????IO????(IOPS)??
???????IO???????????????????д????????????????ζ?д??????????????IO?????????IO??????????????
????????????????????????IOPS????????????????Linux???????????????iostat???????Щ?????
[hbase@ecs-097 ~]$ iostat -dxk 1
Linux 2.6.32-504.3.3.el6.x86_64 (ecs-097)     08/01/2016     _x86_64_    (4 CPU)
avg-cpu:  %user   %nice %system %iowait  %steal   %idle
0.52    0.00    0.13    0.06    0.00   99.28
Device:         rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
xvda              0.10     6.63    0.40    2.57     6.22    36.80    29.00     0.04   14.63   1.19   0.35
????(?豸)?????????????д???I/O???????????????????????iostat????е?%util????????????60%??????????????????????
????IOPS????????/д?????????????iostat????е?r/s??w/s??????PC???е???IOPS?????100????????????????/???????????????????????????????????????????÷???????IOPS???????????????????м???????IOPS????????????????????????????????IO????
????????????????????/д???????С????iostat????е?rkB/s??wkB/s??????????????????????IO????????????????IO???????????????????????д???????????????????IO?????IO?μ??????????????????????????????б???????
??????. Network
???????籾????????????????????????????????????????????????????????????У??????????????????????????????????????????????????????·?????????????????????????????????????????????????????????????????????е??????????????????????????????????????????????У????????????????????????
??????Linuxf???????????????iptraf?????????????????????磺
[root@ecs-097 ~]# iptraf -d eth0
x Total rates:         67.8 kbits/sec        Broadcast packets:            0x
x                      54.2 packets/sec      Broadcast bytes:              0                                                                                                                x
x                                                                                                                                                                                           x
x Incoming rates:      19.2 kbits/sec                                                                                                                                                       x
x                      25.4 packets/sec                                                                                                                                                     x
x                                            IP checksum errors:           0                                                                                                                x
x Outgoing rates:      48.7 kbits/sec                                                                                                                                                       x
x                      28.8 packets/sec
??????. ???
????????????У???????????????????????????????????????????????????塣
???????????????????????????У?????CPU?????????????????????????????????????Щ??????Linux????????????????
?????????????У??????????????Щ??????????nmon??JMeter??PerfMon????????zabbix????????????????????????????