如何使用nfsiostat来分析nfs存储性能问题

nfsiostat介绍

Sysstat家族包括一个名叫nfsiostat的实用程序，它和iostat有诸多类似之处，它允许你监控NFS文件系统上的读写情况，其用法也和iostat类似，最基本的命令用法是跟上几个参数和两个数字，这两个数字分别表示：(1)nfsiostat输出的间隔时间，(2)运行nfsiostat的次数，如果第二个数字留空，nfsiostat会一直执行下去，直到你按下^c停止它。

nfsiost 输出结果介绍

op/s
This is the number of operations per second.

rpc bklog
This is the length of the backlog queue.

kB/s
This is the number of kB written/read per second.

kB/op
This is the number of kB written/read per each operation.

retrans
This is the number of retransmissions.

avg RTT (ms)
This is the duration from the time that client's kernel sends the RPC request until the time it receives the reply.

avg exe (ms)
This is the duration from the time that NFS client does the RPC request to its kernel until the RPC request is completed, this includes the RTT time above.

avg RTT 可以用来做为nfs 存储性能分析的数据。 如果过高的话，就说明从存储端的延迟比较高。
更多的分析数据，可以参考原文。如何利用nfsiostat去查看nfs 存储的性能问题