OpenVMS Cluster Systems - OpenVMS Systems - HP

Potential Hot Files Methods to Help
Move these high-activity files off
the system disk:
• SYSUAF.DAT
• NETPROXY.DAT
• RIGHTSLIST.DAT
• ACCOUNTNG.DAT
• VMSMAIL_PROFILE.DATA
• QMAN$MASTER.DAT
• †VMS$OBJECTS.DAT
• Layered product and other
application files
†VAX specific
Building Large OpenVMS Cluster Systems
9.5 System-Disk Throughput
Use any of the following methods:
• Specify new locations for the files according to the
instructions in Chapter 5.
• Use caching in the HSC subsystem or in RF or RZ disks to
improve the effective system-disk throughput.
• Add a solid-state disk to your configuration. These devices
have lower latencies and can handle a higher request rate
than a regular magnetic disk. A solid-state disk can be used
as a system disk or to hold system files.
• Use DECram software to create RAMdisks on MOP servers
to hold copies of selected hot read-only files to improve boot
times. A RAMdisk is an area of main memory within a
system that is set aside to store data, but it is accessed as if
it were a disk.
Moving these files from the system disk to a separate disk eliminates most of the
write activity to the system disk. This raises the read/write ratio and, if you are
using Volume Shadowing for OpenVMS, maximizes the performance of shadowing
on the system disk.
9.5.3 Configuring Multiple System Disks
Depending on the number of computers to be included in a large cluster and the
work being done, you must evaluate the tradeoffs involved in configuring a single
system disk or multiple system disks.
While a single system disk is easier to manage, a large cluster often requires
more system disk I/O capacity than a single system disk can provide. To achieve
satisfactory performance, multiple system disks may be needed. However,
you should recognize the increased system management efforts involved in
maintaining multiple system disks.
Consider the following when determining the need for multiple system disks:
• Concurrent user activity
In clusters with many satellites, the amount and type of user activity on those
satellites influence system-disk load and, therefore, the number of satellites
that can be supported by a single system disk. For example:
IF... THEN... Comments
Many users are active or
run multiple applications
simultaneously
The load on the system disk can
be significant; multiple system
disks may be required.
Some OpenVMS Cluster systems may need to
be configured on the assumption that all users
are constantly active. Such working conditions
may require a larger, more expensive OpenVMS
Cluster system that handles peak loads without
performance degradation.
Building Large OpenVMS Cluster Systems 9–15