Efficient accumulation of performance statistics in a multi-port network

Abstract

Computer networks are provided with a resource efficient ability to generate link performance statistics. To calculate the average link utilization per I/O operation, a first counter accumulates the number of I/O operations processed by a link and a second counter accumulates the time required by the link to complete each I/O operation. The second value is then divided by the first value. The number of operations per second for a link may be computed by dividing the first number by a predetermined period of time and the average number of operations using the link may be computed by dividing the second number by the predetermined period of time. A third counter may be employed to accumulate the number of bytes transferred by a link during each I/O operation. Then, average size of an I/O operation may be computed by dividing the third number by the first number and the average bandwidth per link operation may be computed by dividing the third number by the predetermined period of time. Separate sets of counters are preferably associated with each of several link types associated with a single port, thereby allowing separate statistics to be generated for each link type. The generated statistics are useful for such activities as problem resolution, load balancing and capacity planning.

1 . A method for computing statistics in a multi-port data network, comprising: 
 for each port in the network: 
 accumulating a number A of I/O operations processed by a link coupled to the port; and  
 accumulating a time B required by the link to complete each I/O operation;  
   selecting a time period ΔT during which statistics are desired;    for each port in the network, calculating the average link utilization per operation ΔB/ΔA; and    outputting the statistics for analysis.    
   
   
       2 . The method of  claim 1 , further comprising: 
 for each port in the network, accumulating a number C of bytes transferred during each I/O operation; and    for each port in the network: 
 calculating operations per second ΔA/ΔT, where ΔA equals the number of I/O operations processed by the link during the time period ΔT;  
 calculating average number of operations using the link ΔB/ΔT, where ΔB equals the time required by the link to complete each I/O operation during the time period ΔT;  
 calculating MB/sec ΔC/ΔT, where ΔC equals the number of bytes transferred during each I/O operation processed by the link during the time period ΔT; and  
 calculating the average bandwidth per operation ΔC/ΔA.  
   
   
   
       3 . The method of  claim 1 , wherein: 
 a plurality of link types are associated with each of at least two ports in the network; and    the steps of accumulating and calculating comprise accumulating and calculating for each link associated with each port.    
   
   
       4 . The method of  claim 3 , wherein the link types are selected from the group comprising ECKD links, PPRC links and SCSI links.  
   
   
       5 . The method of  claim 1 , wherein calculating is performed by a storage server attached to the network.  
   
   
       6 . The method of  claim 1 , wherein selecting the time period ΔT comprises receiving input from a system administrator.  
   
   
       7 . A computer program product of a computer readable medium usable with a programmable computer, the computer program product having computer-readable code embodied therein for for computing statistics in a multi-port data network, the computer-readable code comprising instructions for: 
 for each port in the network: 
 accumulating a number A of I/O operations processed by a link coupled to the port; and  
 accumulating a time B required by the link to complete each I/O operation;  
   selecting a time period ΔT during which statistics are desired;    for each port in the network calculating the average link utilization per operation ΔB/ΔA; and    outputting the statistics for analysis.    
   
   
       8 . The computer program product of  claim 7 , 
 for each port in the network, accumulating a number C of bytes transferred during each I/O operation; and    for each port in the network: 
 calculating operations per second ΔA/ΔT, where ΔA equals the number of I/O operations processed by the link during the time period ΔT;  
 calculating average number of operations using the link ΔB/ΔT, where ΔB equals the time required by the link to complete each I/O operation during the time period ΔT;  
 calculating MB/sec ΔC/ΔT, where ΔC equals the number of bytes transferred during each I/O operation processed by the link during the time period ΔT; and  
   calculating the average bandwidth per operation ΔC/ΔA.    
   
   
       9 . The computer program product of  claim 7 , wherein: 
 a plurality of link types are associated with each of at least two ports in the network; and    the instructions for accumulating and calculating comprise instructions for accumulating and calculating for each link associated with each port.    
   
   
       10 . The computer program product of  claim 9 , wherein the link types are selected from the group comprising ECKD links, PPRC links and SCSI links.  
   
   
       11 . The computer program product of  claim 7 , wherein the instructions for selecting the time period ΔT comprise instructions for receiving input from a system administrator.