????
Virtual Memory

??????????????妫�??????????????????妫�?????????????????????????????(SWAP)?????????????????(Virtual Memory)???????????????????????????????????????????????????????????????SWAP???写??????????????妫�????????????swap???????????????????????????????姹�????(x86????????小?4k)??????写?????????????位?????????????????????????????????????????????????娲�???????SWAP????????????swap??????????????????????娼�??(Paging)??
???????????(free memory)?????????????????vmstat???free?????????????小?????????????????效?????????????械?????free???????围?????????????????20%?????????????小??????????80%??????????????????????????????????????????娼�????????卸????????????????????娼�????????????????????????????????????????????
??????娼�??(Paging)????娼�????????SWAP?????????????娼�????SWAP??????????????????娼�???????????????????vmstat??si??so?????
????· si??????SWAP??????????????小
????· so?????????写??SWAP???????小
????SWAP??????:?????vmstat??swpd????????SWAP??????????????煤???娼�????????????????绲眘wpd???0????si??so?????????0?????????????谐???????????
??????. Disk
???????????????????????????????????????????????SSD?????写???????娑�????????????????????????CPU????????????????????IO??????IO?????IO??????????????????????????????????????????????
???????IO???????写???????写???????味?写??????????小????IO??????????????????IO????(IOPS)??
???????IO???????????????????写????????????????味?写??????????????IO?????????IO??????????????
????????????????????????IOPS????????????????Linux???????????????iostat???????些?????
[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
????(?璞�)?????????????写???I/O???????????????????????iostat????械?%util????????????60%??????????????????????
????IOPS????????/写?????????????iostat????械?r/s??w/s??????PC???械???IOPS?????100????????????????/???????????????????????????????????????????梅???????IOPS???????????????????屑???????IOPS????????????????????????????????IO????
????????????????????/写???????小????iostat????械?rkB/s??wkB/s??????????????????????IO????????????????IO???????????????????????写???????????????????IO?????IO?渭??????????????????????????????斜???????
??????. Network
???????绫�????????????????????????????????????????????????????????????校??????????????????????????????????????????????????????路?????????????????????????????????????????????????????????????????????械??????????????????????????????????????????????校????????????????????????
??????Linuxf???????????????iptraf?????????????????????纾�
[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
??????. ???
????????????校???????????????????????????????????????????????????濉�
???????????????????????????校?????CPU?????????????????????????????????????些??????Linux????????????????
?????????????校??????????????些??????????nmon??JMeter??PerfMon????????zabbix????????????????????????????