Tape Performance check list

Answer

The following is a list of items to check for poor tape performance, however, this list should only be considered a starting point:

1) Verify the device drivers are up to date.
2) Check that the firmware is up to date.
3) Determine if the disk and tape share the same HBA/Port as this configuration is not recommended.
4) Determine if the number of tape drives and if their total throughput is greater than the HBA/port capacity. Example:
Physical 3584 with 15 3592E06 drives
Each drive capable of  160MBytes/sec
HBA 4Gbit/sec is 500MB/sec
 
This would indicate 3 or possibly 4 drives could be used on the HBA Port
( 3x160MB=480MB or 4x160MB=640MB)
4 or 5 HBA ports would be needed for the 15 drives. HBA's may be either single or dual port.
5) Determine if the switch port where the HBA connects (with tape devices) has the same or greater throughput as the HBA. Note: In the following example the switch can only handle 2 Gbits where the HBA can handle 4Gbits. The switch port would be the bottleneck:
Example on AIX:
fcstat fcs0                                            
FIBRE CHANNEL STATISTICS REPORT: fcs0                  
                                                     
Device Type: 4Gb FC PCI Express Adapter (df1000fe)    
 (adapter/pciex/df1000fe)                                            
Serial Number: 1A122002C6                                          
Option ROM Version: 02E8277F                                        
ZA: Z1F2.70A5                                                      
World Wide Node Name: 0x20000000C9BAD4DE                            
World Wide Port Name: 0x10000000C9BAD4DE                            
FC-4 TYPES:                                                        
  Supported:                                                        
0x0000012000000000000000000000000000000000000000000000000000000000  
  Active:                                                          
0x0000010000000000000000000000000000000000000000000000000000000000  
Class of Service: 3                                                
Port Speed (supported): 4 GBIT                                      
Port Speed (running):   2 GBIT  <----- Here, this indicates the switch port is 2 Gbits