HP OpenVMS for Integrity Servers Versions 8.2-1 and 8.2, and HP OpenVMS Alpha Version 8.2 (15320)

ManualsBrandsHP ManualsSoftwareHP OpenVMS I64 v8.3 Software

HP OpenVMS for Integrity Servers Versions 8.2-1 and 8.2, and HP OpenVMS Alpha Version 8.2 SPD 82.35.08

OPERATING SYSTEM ENVIRONMENT

Processes and Scheduling

Executable images consist of system programs and

user programs that have been compiled and linked.

These images run in the context of a process on Open-

VMS systems. Sixty-four process priorities are recog-

nized on OpenVMS Alpha and OpenVMS I64. Priorities

0 to 15 are for time-sharing processes and applications

(four is the typical default for timesharing processes).

Priorities 16 to 63 on Alpha and Integrity servers are

for real-time processes. Real-time processes can be

assigned higher priorities to ensure that they receive

processor time whenever they are ready to execute.

OpenVMS uses paging and swapping to provide suf-

ﬁcient virtual memory for concurrently executing pro-

cesses. Paging and swapping is also provided for pro-

cesses whose memory requirements exceed available

physical memory.

64-Bit Virtual Addressing

The OpenVMS Alpha and OpenVMS I64 operating sys-

tems provide support for 64-bit virtual memory address-

ing. This capability makes the 8 TB virtual address

space available to the OpenVMS Alpha and OpenVMS

I64 operating systems and to application programs. Fu-

ture hardware implementations for Integrity servers will

provide greater capacity. OpenVMS applications can

take advantage of 64-bit processing by using 64-bit data

types supported by the compilers. Refer to the SPDs

for the OpenVMS Alpha and OpenVMS I64 compilers

for further details.

Very Large Memory (VLM) Features

OpenVMS Alpha and OpenVMS I64 provide the follow-

ing additional memory management VLM features be-

yond those provided by 64-bit virtual addressing. These

features can be used by database servers to keep large

amounts of data in memory, resulting in dramatically in-

creased runtime performance. The VLM features pro-

vided by OpenVMS Alpha and OpenVMS I64 are:

• Memory-resident global sections

• Fast I/O for global sections

• Shared page tables

• Expandable global page table

• Reserved memory registry

DECdtm Services

The DECdtm services embedded in the OpenVMS op-

erating system support fully distributed databases us-

ing a two-phase commit protocol. The DECdtm ser-

vices provide the technology and features for distributed

processing, ensuring both transaction and database in-

tegrity across multiple HP resource managers. Updates

to distributed databases occur as a single all-or-nothing

unit of work, regardless of where the data physically re-

sides. This ensures the consistency of distributed data.

DECdtm services allow applications to deﬁne global

transactions that can include calls to any number of HP

data management products. Regardless of the mix of

data management products used, the global transac-

tion either commits or aborts. OpenVMS is unique in

providing transaction processing functionality with base

operating system services.

DECdtm features include:

• Embedded OpenVMS system services that support

the DECtp architecture, providing the features and

technology for distributed transaction processing.

• Ability for multiple disjoint resources to be updated

automatically. These resources can be either physi-

cally disjointed on different clusters at separate sites,

or logically disjointed in different databases on the

same node.

• Ability to use the X/Open Distributed Transaction

Processing XA interface that enables the DECdtm

transaction manager to coordinate XA-compliant re-

source managers (the HP DECdtm XA Veneer), and

XA-compliant transaction processing systems to co-

ordinate DECdtm-compliant resource managers (the

DECdtm XA Gateway).

• Robust application development. Applications can

be written to ensure that data is never in an incon-

sistent state, even in the event of system failures.

• Ability to be called using any HP TP monitor or

database product. This is useful for applications us-

ing several HP database products.

Interprocess Communication

OpenVMS provides the following facilities for applica-

tions that consist of multiple cooperating processes:

• Mailboxes as virtual devices that allow processes to

communicate with queued messages.

• Shared memory sections on a single processor or an

SMP system that permit multiple processes to access

shared address space concurrently.

• Galaxywide sections on a Galaxy platform that permit

multiple processes in multiple instances to access

shared address space concurrently.