Question

I run a FreeBSD NFS server and recently I’ve been having odd issues throughout the cluster (the Apache servers are hanging in “lockf” state when loading files from the NFS share, etc).

I’m fairly new to this, so my question is how can I tell if a server’s IO is getting overloaded?

Here is my current iostat:

[root@host ~]# iostat 1 10  
      tty           mfid0             cpu  
 tin tout  KB/t tps  MB/s  us ni sy in id  
   0   55 16.03 194  3.04   0  0  5  0 95  
   0  490 21.73 238  5.05   0  0  5  0 95  
   0   43 20.09 402  7.88   0  0  7  0 93  
   0  407 12.58 531  6.53   0  0  5  0 94  
   0   43 15.69 416  6.37   0  0  8  1 91  
   0  437 30.23 287  8.46   0  0  9  1 91  
   0   43 23.50 109  2.50   0  0  2  0 98  
   0  273 11.58  76  0.86   0  0  2  0 98  
   0   43 15.70 243  3.72   0  0  5  0 95  
   0  320 20.35 248  4.92   0  0  3  0 96  
[root@host ~]#

Do any of the values seem high? Are there any other tests I can do to see if the system is handling the load efficiently?

Thanks!

Answer 1

Try using gstat or systat -iostat but it will only show you (like iostat) IO usage not what causes it. You probably are more interested in trying:
procstat -f $ApachePIDinLockfState

or
ktrace -p $ApachePIDinLockfState and kdump -R | less. Remeber to run ktrace -C when you have finished.