HP Integrity NonStop J-Series - Manual (Page 92)

Guardian Performance Analyzer (GPA) User Guide
– (544541-006) Page 92 of 131
Cache Performance Analysis
In the Cache Performance Analysis section of the report (Example 4-15), GPA analyzes
the cache performance for each disk volume on the node by the four sizes of blocks,
512, 1024, 2048, and 4096 bytes, used in the system. For each volume and each
block size, the table shows the number of blocks allocated to cache, the percentage of
cache hits, and the number of requests per second.
Example 4-15. Cache Performance Analysis for \NODEB
CACHE PERFORMANCE ANALYSIS
LOGICAL | ALLOCATED CACHE | CACHE HIT RATES(%) | REQUEST RATES
VOLUME | 512 1024 2048 4096 | 512 1024 2048 4096 | CACHE BLOCK/SECOND
| BLKS BLKS BLKS BLKS | | 512 1024 2048 4096
| | |
$SYSTEM | 16 30 10 50 | 99 99 66 87 | .2 1.4 .4
$PRODl | 180 6 7 30 | 96 99 46 | 3.2
$PROD4 | 8 6 6 63 | 90 83 | 14.0
$PROD3 | 8 380 10 73 | 78 76 77 77 | .1 .2 9.4
$TEST3 | 8 6 6 6 | 98 93 | .2 1.9
$PROD5 | 8 6 6 25 | 93 90 91 96 | 1.7
$PROD2 | 8 6 6 6 | 89 97 | .2
$TESTl | 8 6 6 6 | |
$TEST2 | 8 6 6 6 | 95 |
In the example, you can see that volumes $PROD4 and $PROD3, with request rates of
14.0 and 9.7 per second for all cache blocks, account for most of the cache activity on
their respective primary processors, CPU 0 and CPU 2. The fact that the same two
volumes also exhibit poor cache performance, as indicated by the relatively low cache
hit rates for their blocks, shows that a reallocation of cache blocks would probably
improve the cache performance for the two volumes. The improved cache
performance should also bring down to acceptable levels the queue times for $PROD4
and $PROD3. On the basis of its cache performance analysis, GPA makes
recommendations for resetting cache allocations to improve performance.
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