HP RX8620-32 - Manual (Page 32)

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Instant Capacity
Instant Capacity is a means of adding and removing CPUs in a partition. With Instant Capacity, you
don’t need to worry about the following:
• Interleaved memory
• Application-locked memory
• Server switchovers due to false failures
• Physically handling CPU or memory boards
• Rebooting
Instant Capacity is the most reliable means of reducing planned downtime for hardware upgrades. It
is only supported with HP-UX at this time.
Memory protection
Main memory failures are the single largest cause of customer downtime. The Integrity rx7620-16 and
rx8620-32 Servers have several features designed to reduce or eliminate failures of memory:
• Chip spare tolerance
• Dynamic memory resiliency (DMR)
• Automatic deconfigure on reboot
• Hardware memory scrubbing
• Industry leadership address/control parity protection
Chip spare tolerance is the ability of the system to continue to run in the face of any single- or multi-bit
chip error on a DRAM. The DRAMs in the Integrity rx7620-16 and rx8620-32 Servers can be thought
of as N+1 per set of 128 DRAMs. This functionality is essential in the design of reliable memory
systems, and systems without this feature are doomed to fail at an alarming rate compared to the
Integrity rx7620-16 and rx8620-32 Servers. (This has been demonstrated at customer sites that use
both chip spare tolerance and less reliable architectures.)
There are many ways that DRAMs can fail, especially when a system has hundreds of them. It is
hopeless to try to design around (or explain away) this simple fact. With HP’s chip spare technology,
the Integrity rx7620-16 and rx8620-32 Server memory is extremely reliable.
Dynamic memory resiliency (DMR)
Dynamic memory resiliency is the system’s ability to de-allocate failed memory pages online. This
feature is similar to dynamic processor resiliency; if a location in memory proves to be questionable
(that is, exhibits persistent errors), the memory is de-allocated online with no customer-visible impact.
Assuming the Integrity rx7620-16 and rx8620-32 Servers are equipped with adequate memory to
begin with, it is likely that the failed memory will never have to be replaced over the life of the
product, resulting in a significant reduction in both planned and unplanned downtime. DMR is
superior to industry-available hardware-only techniques because hardware-only techniques can
quickly run out of spares. HP’s page de-allocation technique solves this problem, resulting in more
spares than can possibly be used over the life of the machine.
Hardware memory scrubbing
Software-based memory scrubbers are limited in function due to the fact that many operating systems
and applications “lock down” memory, resulting in no possible access. HP’s hardware scrubber
“cleans” memory without OS or application knowledge, resulting in much better coverage.