I/O、内存、网络性能优化命令 iostat , vmstat,netstat

小灰灰 2022-08-12 05:58 80阅读 0赞

原贴:http://www.cndw.com/tech/server/2006040430550.asp  
  
是在sun网站上看到的，原文是e文，连接如下：  
[http://www.adminschoice.com/docs/iostat\_vmstat\_netstat.htm ][http_www.adminschoice.com_docs_iostat_vmstat_netstat.htm]  
  
大概翻译了一下，总觉得好像以前哪位大大贴过类似的  
不管了，觉得有点用，大家一起看看  
翻译得不好，见笑了……如果有错，请指正哦，先谢了  
  
Input Output statistics ( iostat )  
  
iostat反映了终端、磁盘I/O情况和CPU活动。输出结果的第一行是从系统启动到现在为止的这段时间的结果，接下去的每一行是interval时  
  
间段内的结果。Kernel里有一组计数器用来跟踪这些值。  
iostat的默认参数是tdc(terminal, disk, and CPU)。如果任何其他的选项被指定，这个默认参数将被完全替代，例如，iostat -d将只反  
  
映磁盘的统计结果。  
  
语法:  
  
基本语法： iostat <options> interval count  
  
option - 让你指定所需信息的设备，像磁盘、cpu或者终端(-d , -c , -t or -tdc ) 。x 选项给出了完整的统计结果（gives the extended  
  
statistic）。  
  
interval - 在两个samples之间的时间（秒）。  
  
count - 就是需要统计几次  
  
例子：  
  
$ iostat -xtc 5 2  
extended disk statistics tty cpu  
disk r/s w/s Kr/s Kw/s wait actv svc\_t %w %b tin tout us sy wt id  
sd0 2.6 3.0 20.7 22.7 0.1 0.2 59.2 6 19 0 84 3 85 11 0  
sd1 4.2 1.0 33.5 8.0 0.0 0.2 47.2 2 23  
sd2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0  
sd3 10.2 1.6 51.4 12.8 0.1 0.3 31.2 3 31  
  
  
The fields have the following meanings:  
  
disk name of the disk  
r/s reads per second  
w/s writes per second  
Kr/s kilobytes read per second  
Kw/s kilobytes written per second  
wait average number of transactions waiting for service (Q length)  
actv average number of transactions actively  
being serviced (removed from the  
queue but not yet  
completed)  
%w percent of time there are transactions waiting  
for service (queue non-empty)  
%b percent of time the disk is busy (transactions  
in progress)  
  
  
  
  
Results and Solutions:  
  
从iostat输出结果中需要注意的值：  
  
Reads/writes per second (r/s , w/s)  
Percentage busy (%b)  
Service time (svc\_t)  
  
如果磁盘显示长时间的高reads/writes，并且磁盘的percentage busy (%b)也远大于5%，同时average service time (svc\_t)也远大于30  
  
milliseconds，这以下的措施需要被执行：  
1.)调整应用，令其使用磁盘i/o更加有效率，可以通过修改磁盘队列、使用应用服务器的cache  
  
2.)将文件系统分布到2个或多个磁盘上，并使用volume manager/disksuite的条带化特点  
  
3.) 增加系统参数值，如inode cache , ufs\_ninode。Increase the system parameter values for inode cache , ufs\_ninode , which  
  
is Number of inodes to be held in memory. Inodes are cached globally (for UFS), not on a per-file system basis  
  
4.) 将文件系统移到更快的磁盘/控制器，或者用更好的设备来代替  
  
还有两段等会翻好了再贴……  
  
Virtual Memory Statistics ( vmstat )  
  
vmstat - vmstat反映了进程的虚拟内存、虚拟内存、磁盘、trap(是不是翻译成中断？？)和cpu的活动情况  
  
在多cpu系统中，vmstat在输出结果中平均了cpu数量。For per-process statistics .如果没有选项，vmstat显示一行虚拟内存活动的概要  
  
结果，是从系统启动时开始的。  
  
语法:  
  
vmstat <options> interval count  
  
option - 让你指定所需的信息类型，例如 paging -p , cache -c ,.interrupt -i etc.  
  
如果没有指定选项，将会显示进程、内存、页、磁盘、中断和cpu信息  
  
interval - 同iostat  
  
count - 同iostat  
  
例子  
The following command displays a summary of what the system  
is doing every five seconds.  
  
example% vmstat 5  
procs memory page disk faults cpu  
r b w swap free re mf pi p fr de sr s0 s1 s2 s3 in sy cs us sy id  
0 0 0 11456 4120 1 41 19 1 3 0 2 0 4 0 0 48 112 130 4 14 82  
0 0 1 10132 4280 0 4 44 0 0 0 0 0 23 0 0 211 230 144 3 35 62  
0 0 1 10132 4616 0 0 20 0 0 0 0 0 19 0 0 150 172 146 3 33 64  
0 0 1 10132 5292 0 0 9 0 0 0 0 0 21 0 0 165 105 130 1 21 78  
  
  
  
  
The fields of vmstat's display are  
procs  
r in run queue  
b blocked for resources I/O, paging etc.  
w swapped  
  
memory (in Kbytes)  
swap - amount of swap space currently available  
free - size of the free list  
  
page ( in units per second).  
re page reclaims - see -S option for how this field is modified.  
mf minor faults - see -S option for how this field is modified.  
pi kilobytes paged in  
po kilobytes paged out  
fr kilobytes freed  
de anticipated short-term memory shortfall (Kbytes)  
sr pages scanned by clock algorithm  
  
disk ( operations per second )  
There are slots for up to four disks, labeled with a single letter and number.  
The letter indicates the type of disk (s = SCSI, i = IPI, etc) . The number is  
the logical unit number.  
  
faults  
in (non clock) device interrupts  
sy system calls  
cs CPU context switches  
  
cpu - breakdown of percentage usage of CPU time. On multiprocessors this is an a  
verage across all processors.  
us user time  
sy system time  
id idle time  
  
结果和解决方案:  
  
A. CPU issues:  
  
下面几列需要被察看，以确定cpu是否有问题  
  
Processes in the run queue (procs r)  
User time (cpu us)  
System time (cpu sy)  
Idle time (cpu id)  
procs cpu  
r b w us sy id  
0 0 0 4 14 82  
0 0 1 3 35 62  
0 0 1 3 33 64  
0 0 1 1 21 78  
  
  
  
问题情况:  
1.) 如果processes in run queue (procs r)的数量远大于系统中cpu的数量，将会使系统便慢。  
2.) 如果这个数量是cpu的4倍的话，说明系统正面临cpu能力短缺,这将使系统运行速度大幅度降低  
3.) 如果cpu的idle时间经常为0的话，或者系统占用时间(cpu sy)是用户占用时间(cpu us)两辈的话，系统面临缺少cpu资源  
  
解决方案 :  
解决这些情况，涉及到调整应用程序，使其能更有效的使用cpu，同时增加cpu的能力或数量。  
  
B. Memory Issues:  
内存的瓶颈取决于scan rate (sr) 。scan rate是每秒时钟对页的扫描 （he scan rate is the pages scanned by the clock algorithm per  
  
second.）如果 scan rate (sr)一直大于200 pages每秒，这时就是内存短缺的现实。  
  
解决方案 :  
1. 调整应用和服务器，使其能更好的使用memory和cache  
2. 增加系统内存  
3. Implement priority paging in s in pre solaris 8 versions by adding line "set priority paging=1" in  
/etc/system. Remove this line if upgrading from Solaris 7 to 8 & retaining old /etc/system file.  
  
Network Statistics (netstat)  
  
netstat通过选项来显示不通的网络相关的数据结构（netstat displays the contents of various network-related data structures  
  
in depending on the options selected.）  
  
语法 :  
  
netstat <option/s>  
  
多个选项可以同时使用  
  
Options  
  
\-a - displays the state of all sockets.  
\-r - shows the system routing tables  
\-i - gives statistics on a per-interface basis.  
\-m - displays information from the network memory buffers. On Solaris, this shows statistics  
forSTREAMS  
\-p \[proto\] - retrieves statistics for the specified protocol  
\-s - shows per-protocol statistics. (some implementations allow -ss to remove fileds with a value of 0 (zero) from the  
  
display.)  
\-D - display the status of DHCP configured interfaces.  
\-n do not lookup hostnames, display only IP addresses.  
\-d (with -i) displays dropped packets per interface.  
\-I \[interface\] retrieve information about only the specified interface.  
\-v be verbose  
interval - number for continuous display of statictics.  
  
Example :  
  
$netstat -rn  
  
Routing Table: IPv4  
Destination Gateway Flags Ref Use Interface  
\-------------------- -------------------- ----- ----- ------ ---------  
192.168.1.0 192.168.1.11 U 1 1444 le0  
224.0.0.0 192.168.1.11 U 1 0 le0  
default 192.168.1.1 UG 1 68276  
127.0.0.1 127.0.0.1 UH 1 10497 lo0  
  
这个显示了一台solaris机器的ip为192.168.1.11，他的默认网关192.168.1.1  
  
结果和解决方案:  
  
A.)网络连通  
  
上面的命令经常用来检查网络的连通性。特别是当机器无法访问外部网络时：  
  
1. 默认路由ip是否正确  
  
2. 能否ping通网关  
  
3. 如果网关地址不对，可以使用route add命令，参考 man route  
  
route command examples:  
$route add default <hostname>  
$route add 192.0.2.32 <gateway\_name>  
If the router address is correct but still you can't ping it there may be some network cable /hub/switch problem and you  
  
have to try and eliminate the faulty component .  
  
  
  
B.) 网络反映  
  
$ netstat -i  
  
Name Mtu Net/Dest Address Ipkts Ierrs Opkts Oerrs Collis Queue  
lo0 8232 loopback localhost 77814 0 77814 0 0 0  
hme0 1500 server1 server1 10658566 3 4832511 0 279257 0  
  
这个选项用于诊断网络问题，网络连通但连接速度慢  
  
Values to look at:  
  
Collisions (Collis)  
Output packets (Opkts)  
Input errors (Ierrs)  
Input packets (Ipkts)  
The above values will give information to workout  
  
i. Network collision rate(网络冲突率)如下 :  
  
Network collision rate = Output collision counts / Output packets  
  
网络冲突率大于10%就显示，网络负载过大、网络配置不正确、硬件问题  
  
ii. Input packet error rate（进入包错误率）如下 :  
  
Input Packet Error Rate = Ierrs / Ipkts.  
  
如果input error rate高（ver 0.25 percent），这个主机就正在丢包。hub/switch 连线就需要被检查是否存在潜在的问题。  
  
C. Network socket & TCP Cconnection state  
netstat给出了关于网络socket和tcp state的重要信息。只是非常有用的，在寻找开放、关闭和等待网络tcp连接。  
netstat返回如下的网络状态 :  
CLOSED ---- Closed. The socket is not being used.  
LISTEN ---- Listening for incoming connections.  
SYN\_SENT ---- Actively trying to establish connection.  
SYN\_RECEIVED ---- Initial synchronization of the connection under way.  
ESTABLISHED ---- Connection has been established.  
CLOSE\_WAIT ---- Remote shut down; waiting for the socket to close.  
FIN\_WAIT\_1 ---- Socket closed; shutting down connection.  
CLOSING ---- Closed, then remote shutdown; awaiting acknowledgement.  
LAST\_ACK ---- Remote shut down, then closed ;awaiting acknowledgement.  
FIN\_WAIT\_2 ---- Socket closed; waiting for shutdown from remote.  
TIME\_WAIT ---- Wait after close for remote shutdown retransmission.  
  
  
Example:  
  
\#netstat -a  
  
  
Local Address Remote Address Swind Send-Q Rwind Recv-Q State  
\*.\* \*.\* 0 0 24576 0 IDLE  
\*.22 \*.\* 0 0 24576 0 LISTEN  
\*.22 \*.\* 0 0 24576 0 LISTEN  
\*.\* \*.\* 0 0 24576 0 IDLE  
\*.32771 \*.\* 0 0 24576 0 LISTEN  
\*.4045 \*.\* 0 0 24576 0 LISTEN  
\*.25 \*.\* 0 0 24576 0 LISTEN  
\*.5987 \*.\* 0 0 24576 0 LISTEN  
\*.898 \*.\* 0 0 24576 0 LISTEN  
\*.32772 \*.\* 0 0 24576 0 LISTEN  
\*.32775 \*.\* 0 0 24576 0 LISTEN  
\*.32776 \*.\* 0 0 24576 0 LISTEN  
\*.\* \*.\* 0 0 24576 0 IDLE  
192.168.1.184.22 192.168.1.186.50457 41992 0 24616 0 ESTABLISHED  
192.168.1.184.22 192.168.1.186.56806 38912 0 24616 0 ESTABLISHED  
192.168.1.184.22 192.168.1.183.58672 18048 0 24616 0 ESTABLISHED  
  
  
if you see a lots of connections in FIN\_WAIT state tcp/ip parameters have to be tuned because the  
connections are not being closed and they gets accumulating . After some time system may run out of  
resource . TCP parameter can be tuned to define a time out so that connections can be released and  
used by new connection.  
A detailed document about tuning tcp/ip can be found at  
[http://www.sean.de/Solaris/soltune.html ][http_www.sean.de_Solaris_soltune.html]

[http_www.adminschoice.com_docs_iostat_vmstat_netstat.htm]: http://www.adminschoice.com/docs/iostat_vmstat_netstat.htm
[http_www.sean.de_Solaris_soltune.html]: http://www.sean.de/Solaris/soltune.html