Mainframe systems hypervolumes
133
Performance and Optimization
Symmetrix DMX-3 supports up to 255 logical volumes per physical
disk drive and up to 64,000 logical volumes (address range 0x000–
0xF9FF) per system, depending on the Symmetrix DMX-3 hardware
configuration and the data protection options.
Note:
“Symmetrix DMX-3 logical volume capacities” on page 66
provides
more information on logical volumes supported on Symmetrix DMX-3 disk
drives and systems. Configuration requirements for Symmetrix systems vary
according to the applications used. To configure logical volumes for optimum
Symmetrix system performance, consult your local EMC Sales
Representative.
Extended cylinder
addressing option
Extended cylinder addressing places a small logical volume at the
end of a disk drive. Each small logical volume can occupy a variable
number of contiguous cylinders. This small logical volume can be as
small as one cylinder in size. The maximum number of cylinders for
this volume depends on the capacity of the disk drive and the
emulation mode selected.
This flexibility in logical volume configuration increases system
performance for datasets requiring extremely high performance such
as Multi-Image Manager files, JES Checkpoint, RACF Control files,
catalogs, and so on.
Because the data of interest resides on a small volume, the Unit
Control Block (UCB) busy conditions that arise when this data is
placed on larger capacity volumes with high activity are eliminated.
This reduces IOSQ (I/O Supervisor Queue Time) exposure and
increases system performance.
Note:
Consult your EMC Systems Engineer regarding dataset placement on
these small logical volumes.
This logical volume can be added to Symmetrix units that are
configured and running without affecting existing data on the disk
drive by giving the volume an address beyond any currently used on
the unit. This option may also be used with the PermaCache option,
in which infrequently accessed datasets requiring instantaneous
access reside permanently in global memory.
Содержание Symmetrix DMX-3
Страница 14: ...EMC Symmetrix DMX 3 Product Guide 14 Figures...
Страница 20: ...20 EMC Symmetrix DMX 3 Product Guide Warnings and Cautions...
Страница 44: ...44 EMC Symmetrix DMX 3 Product Guide Introducing the Symmetrix DMX 3...
Страница 100: ...100 EMC Symmetrix DMX 3 Product Guide Symmetrix DMX 3 Hardware...
Страница 114: ...114 EMC Symmetrix DMX 3 Product Guide Symmetrix DMX 3 Input Output Operations...
Страница 224: ...224 EMC Symmetrix DMX 3 Product Guide Data Integrity Availability and Protection...
Страница 254: ...254 EMC Symmetrix DMX 3 Product Guide Mainframe Features and Support...
Страница 282: ...282 EMC Symmetrix DMX 3 Product Guide Power Sequences...