HP OpenVMS Systems

Ask the Wizard
» 

HP OpenVMS Systems

OpenVMS information
» What's new on our site
» Upcoming events
» Configuration and buying assistance
» Send us your comments

HP OpenVMS systems
» OpenVMS software
» Supported Servers
» OpenVMS virtualization
» OpenVMS solutions and partners
» OpenVMS success stories
» OpenVMS service and support
» OpenVMS resources and information
» OpenVMS documentation
» Education and training

Quick Links
» Non-javascript page
» Ask the Wizard
» OpenVMS FAQ

Test Drive OpenVMS
» OpenVMS I64 test drive
» Java test drive

Other information resources available to you include:
» OpenVMS freeware
» ECO kits, software and hardware support, prior version support
» Alpha SRM, ARC, and AlphaBIOS firmware updates
» ENCOMPASS - HP user group
» OpenVMS software downloads, OpenVMS freeware CD-ROM
» OpenVMS firmware locations
» DECconnect passive adaptor charts
» Cables reference guide
» MicroVAX console commands
» OpenVMS student research

Select a topic below to see Questions Frequently Asked by partners
» Using the online documentation library(installing BNU from the asap SDK)
» Global sections(how to create and use.)
» xx$CREATE_BUFOBJ system service(usage)
» Ethernet address(methods of determination)
» Shareable images(cookbook approach to creating one)
» Sharing data/code at absolute addresses(a guide with examples)
» Determining the Alpha microprocessor
» Using GETSYI to get hardware status

Evolving business value
» Business Systems Evolution
» AlphaServer systems transition planning
» Alpha RetainTrust program

Related links
» HP Integrity servers
» HP Alpha systems
» HP storage
» HP software
» HP products and services
» HP solutions
» HP support
disaster proof
HP Integrity server animation
HP Integrity server animation
Content starts here

Ask the Wizard Questions

Tuning: Extent cache

The Question is: 

When I do a SHOW DEVICE/FULL DIA9, the listing shows information
about the number of blocks in the extent cache. Where do I
find more information about WHAT the extent cache is?

The Answer is: 

    $ mcr sysgen help param acp_extcache

      ACP_EXTCACHE

        ACP_EXTCACHE sets the number of entries in the extent cache.
        Each entry points to one contiguous area of free space on disk.
        A specification of 0 means no cache. Too small a value causes
        excessive XQP I/O operations, while too large a value causes
        excessive physical memory to be consumed by the extent cache.

    Also see Kirby McCoy's File System Internals book.