Optimal performance specifications

The following steps are recommended to achieve optimal journal performance:

Allocate the journal data sets on high-performance volumes, and place them behind storage controls that use DASD fast write, cache functions, and have large NVSs.
Attach the journal data sets with high bandwidth ESCON® or FICON® channels, preferably capable of very high transfer rates.
Allocate the same amount of space for all journal data sets.
Put the journal data set volumes behind storage controls that do not also process primary or secondary volumes.
Spread the striped journal data sets across as many disk volumes as possible, preferably with each journal data set on a separate volume. Processing performance is improved because XRC assigns a separate internal subtask for each pair of allocated journal data sets.
For a fully-configured, active mirror do not use less than four journal data sets.

Table 1 and Table 2 show examples of journal data set patterns for two and eight stripes across four, eight and sixteen journal data sets.

Table 1. Sample Journal Data Set Patterns for Two Stripes
Journal Data Sets	Striped data sets
Two	`VOL1 VOL2 JRNL01 JRNL01 JRNL02 JRNL02`
Four	`VOL1 VOL2 VOL3 VOL4 JRNL01 JRNL01 JRNL03 JRNL03 JRNL02 JRNL02 JRNL04 JRNL04`
Eight	`VOL1 VOL2 VOL3 VOL4 JRNL01 JRNL01 JRNL03 JRNL03 JRNL02 JRNL02 JRNL04 JRNL04 VOL5 VOL6 VOL7 VOL8 JRNL05 JRNL05 JRNL07 JRNL07 JRNL06 JRNL06 JRNL08 JRNL08`
Sixteen	`VOL1 VOL2 VOL3 VOL4 JRNL01 JRNL01 JRNL03 JRNL03 JRNL02 JRNL02 JRNL04 JRNL04 VOL5 VOL6 VOL7 VOL8 JRNL05 JRNL05 JRNL07 JRNL07 JRNL06 JRNL06 JRNL08 JRNL08 VOL9 VOL10 VOL11 VOL12 JRNL09 JRNL09 JRNL11 JRNL11 JRNL10 JRNL10 JRNL12 JRNL12 VOL13 VOL14 VOL15 VOL16 JRNL13 JRNL13 JRNL15 JRNL15 JRNL14 JRNL14 JRNL16 JRNL16`

Journal Data Sets Striped data sets

Four

Table 2. Sample Journal Data Set Patterns for Eight Stripes
Journal Data Sets	Striped data sets
Four	`Vol 1 Vol 2 Vol 3 Vol 4 JRNL01 JRNL01 JRNL01 JRNL01 JRNL02 JRNL02 JRNL02 JRNL02 Vol 5 Vol 6 Vol 7 Vol 8 JRNL01 JRNL01 JRNL01 JRNL01 JRNL02 JRNL02 JRNL02 JRNL02 Vol 9 Vol 10 Vol 11 Vol 12 JRNL03 JRNL03 JRNL03 JRNL03 JRNL04 JRNL04 JRNL04 JRNL04 Vol 13 Vol 14 Vol 15 Vol 16 JRNL03 JRNL03 JRNL03 JRNL03 JRNL04 JRNL04 JRNL04 JRNL04`

 Vol 1       Vol 2       Vol 3       Vol 4     
 JRNL01      JRNL01      JRNL01      JRNL01    
 JRNL02      JRNL02      JRNL02      JRNL02    
                                               
 Vol 5       Vol 6       Vol 7       Vol 8     
 JRNL01      JRNL01      JRNL01      JRNL01    
 JRNL02      JRNL02      JRNL02      JRNL02    
                                               
 Vol 9       Vol 10      Vol 11      Vol 12    
 JRNL03      JRNL03      JRNL03      JRNL03    
 JRNL04      JRNL04      JRNL04      JRNL04    
                                               
 Vol 13      Vol 14      Vol 15      Vol 16    
 JRNL03      JRNL03      JRNL03      JRNL03    
 JRNL04      JRNL04      JRNL04      JRNL04

For additional information about optimizing XRC performance, refer to Maximizing access to journal data sets .