374 IBM TotalStorage DS6000 Series: Performance Monitoring and Tuning
If a significant portion of the I/O response time is connect time, you should get an
understanding of contention from the ESS Link Statistics report (Example 10-7 on page 377)
and Channel Path Activity report (Example 10-3). ESS Link Statistics is better reporting for
multiple CEC systems
daisy chained to a Host Adapter; Channel Path Activity is better for
multiple DS6000 to a FICON channel.
10.9.3 Analyze I/O queuing activity
Example 10-2 shows the report where we can check if the IOP is saturated. An average
queue length greater than one indicates that the IOP is saturated, even though an average
queue length greater than 0.5 should be considered as a warning sign. A burst of I/O can also
trigger a high average queue length.
Example 10-2 I/O queuing activity
I/O Q U E U I N G A C T I V I T Y
z/OS V1R6 SYSTEM ID GDP5 DATE 08/24/2005 INTERVAL 05.00.006
RPT VERSION V1R5 RMF TIME 12.30.00 CYCLE 1.000 SECONDS
TOTAL SAMPLES = 300 IODF = 99 CR-DATE: 07/15/2005 CR-TIME: 11.17.22 ACT: ACTIVATE
- INITIATIVE QUEUE - ------- IOP UTILIZATION ------- -- % I/O REQUESTS RETRIED -- -------- RETRIES / SSCH ---------
IOP ACTIVITY AVG Q % IOP I/O START INTERRUPT CP DP CU DV CP DP CU DV
RATE LNGTH BUSY RATE RATE ALL BUSY BUSY BUSY BUSY ALL BUSY BUSY BUSY BUSY
00 2761.055 0.01 7.03 2761.055 2916.185 0.9 0.8 0.0 0.0 0.0 0.01 0.01 0.00 0.00 0.00
01 381.159 0.00 1.01 381.159 422.858 2.1 2.1 0.0 0.0 0.0 0.02 0.02 0.00 0.00 0.00
SYS 3142.214 0.01 4.02 3142.214 3339.043 1.0 1.0 0.0 0.0 0.0 0.01 0.01 0.00 0.00 0.00
10.9.4 Analyze FICON statistics
The FICON report, as shown in Example 10-3, shows the FICON channel related statistics.
The PART Utilization is the FICON channel utilization by this partition or LPAR, and the Total
Utilization is the total utilization of the FICON channel from all LPARs that are defined on the
CEC. The RoT for the total FICON channel utilization and the BUS utilization is to keep them
under 50%. If these numbers exceed 50%, then you will see an elongated CONN time.
The BUS utilization is always greater than 5%, even if there is no I/O activity at all on the
channel. For small block transfers, the BUS utilization is less than the FICON channel
utilization, and for large block transfers, the BUS utilization is greater than the FICON channel
utilization.
Example 10-3 Channel Path Activity report
C H A N N E L P A T H A C T I V I T Y
z/OS V1R6 SYSTEM ID GDP5 DATE 08/24/2005 INTERVAL 05.00.006
RPT VERSION V1R5 RMF TIME 12.30.00 CYCLE 1.000 SECONDS
IODF = 99 CR-DATE: 07/15/2005 CR-TIME: 11.17.22 ACT: ACTIVATE MODE: LPAR CPMF: EXTENDED MODE
-------------------------------------------------------------------------------------------------------------------------
DETAILS FOR ALL CHANNELS
-------------------------------------------------------------------------------------------------------------------------
CHANNEL PATH UTILIZATION(%) READ(MB/SEC) WRITE(MB/SEC) CHANNEL PATH UTILIZATION(%) READ(MB/SEC) WRITE(MB/SEC)
ID TYPE G SHR PART TOTAL BUS PART TOTAL PART TOTAL ID TYPE G SHR PART TOTAL BUS PART TOTAL PART TOTAL
2E FC_S 2 Y 1.12 1.75 4.92 0.04 0.17 1.75 1.81 36 FC_? 2 Y 0.00 0.13 3.96 0.00 0.00 0.00 0.00
2F FC_S 2 Y 1.10 1.73 4.90 0.04 0.17 1.71 1.77 37 FC_? 2 Y 0.00 0.13 3.96 0.00 0.00 0.00 0.00
30 FC_S 2 Y 0.00 0.14 3.96 0.00 0.00 0.00 0.00 38 FC_S 2 Y 0.00 4.11 4.35 0.00 0.00 0.00 0.00
39 FC_S 2 Y 0.00 3.63 4.29 0.00 0.00 0.00 0.00 43 FC_S 2 Y 11.17 11.17 7.24 2.43 2.43 2.36 2.36
3A FC_S 2 Y 0.00 0.13 3.96 0.00 0.00 0.00 0.00 4A FC_S 2 Y 0.00 0.13 3.96 0.00 0.00 0.00 0.00
3B FC_S 2 Y 0.00 0.14 3.96 0.00 0.00 0.00 0.00 4B FC_S 2 Y 0.00 0.14 3.97 0.00 0.00 0.00 0.00
3C FC_S 2 Y 0.00 1.30 4.07 0.00 0.00 0.00 0.00 4C FC_S 2 Y 4.21 4.21 5.46 0.80 0.80 1.77 1.77
3D FC_S 2 Y 0.00 0.96 4.06 0.00 0.00 0.00 0.00 4D FC_S 2 Y 11.15 11.15 7.26 2.42 2.42 2.43 2.43
FICON Open Exchange
To prevent the DS6000 FICON ports from being overloaded, especially when connected to
multiple CECs, there is a limit set on the number of active channel programs that can be

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