Balancing disk activity – HP NonStop G-Series User Manual
Page 148
Balancing and Tuning a System
Measure User’s Guide — 520560-003
7- 12
Checking and Tuning Problem Areas
To balance the memory requirements across CPUs, you first need to examine the
memory requirements in each CPU. To do this, list the CPUs in order of their SWAPS
counter values:
10+ LIST CPU *, BY SWAPS
Do not accept a high SWAPS value as indicating memory problems without checking
for short-term processes (see item 5 on page
When you know which CPUs have a memory problem and which have enough
memory, balance the memory workload by moving processes from the problem CPUs
to the other CPUs. To determine the memory requirements of each process in a CPU,
list the processes by their PRES-PAGES-QTIME counter values (specify
n
as the
number of the CPU):
20+ LIST PROCESS n,*, BY PRES-PAGES-QTIME
Move processes so that process memory requirements are balanced across CPUs.
Move one process at a time. After moving a process, check the effect of the change. If
you have shifted the memory problem from one CPU to the other, move the process
back and try a process with a smaller memory requirement.
Balancing Disk Activity
These components of the disk subsystem can affect performance:
•
Controllers. On systems running D-series RVUs, multiple disks on each controller
can cause performance problems as the disks compete for use of the controller.
On systems running G-series RVUs, the ServerNet architecture provides faster
response time and higher throughput for I/O requests. Thus, balancing controller
loads for disk activity is generally not a significant performance issue.
•
File system, disk process, and disk. Because these three operate serially, you can
treat them as a single unit for performance analysis. These entities are used to
examine this portion of the disk subsystem:
Balancing disk activity includes:
1. Balance disk processes across CPUs.
By spreading the activity of the primary disk processes evenly across the CPUs,
you prevent the processes from contending with each other for CPU time. For
more information, see
2. Minimize disk I/O operations.
FILE
Examines logical I/O operations on a file
DISCOPEN
Examines physical I/O operations on a file in detail
DISKFILE
Provides an overview of physical I/O operations on a file
PROCESS
Examines the disk process
DISC
Examines physical disk access