Card Interoperability; Proliant Server Transition Strategy - HP ProLiant DL985 Introduction Manual

Card interoperability

The PCI Express specification provides interoperability features. For example, up-plugging (plugging
"small cards" into "big slots") is allowed. However, down-plugging (plugging a "big card" into a
"small slot") is physically prevented. Down-shifting is allowed in one case so that a x8 connector can
be electrically wired (or "plumbed") with a x4 link. Table 1 identifies the possible interoperability
scenarios.
Table 1. PCI Express add-in card interoperability
x1 slot
x1 card
Required
x4 card
Not allowed
x8 card
Not allowed
x16 card
Not allowed

ProLiant server transition strategy

HP is committed to ensuring a smooth transition between I/O standards for customers. HP is
beginning to introduce PCI Express technology into next-generation ProLiant servers to coexist with
PCI-X 133. This will allow ProLiant server customers to install new higher bandwidth cards (for
example, dual 4-Gb Fibre Channel, x4 InfiniBand, and 10-Gb Ethernet) using PCI Express technology
beginning in 2004. At the same time, the continued commitment from HP to PCI-X will allow ProLiant
server customers to connect to their existing I/O cards. HP will begin phasing PCI Express into Smart
Array, ProLiant NIC, and Fibre Channel SAN cards as the technology matures.
PCI Express slots first became available in select ProLiant servers that were introduced in the second
half of 2004. ProLiant ML servers have a mix of PCI-X and PCI Express slots, while ProLiant DL servers
have optional riser cards to provide different combinations of PCI-X and PCI Express slots.
Customers who require peripheral bandwidth in excess of 1 GB/s will likely find those peripherals
implemented with PCI Express technology. It is expected that most device manufacturers will use PCI
Express technology for higher bandwidth peripheral devices such as 10-Gb Ethernet and 10-Gb Fibre
Channel. For peripherals that require bandwidth less than 1 GB/s, PCI and PCI-X will remain viable
technologies and continue to provide backward compatibility. It is anticipated that device vendors will
manufacture peripherals with bandwidth requirements in the 1 GB/s range in two versions, providing
options for customers to choose either PCI Express or PCI-X technology.
x8 plumbed
x4 slot x4 slot
Required Required
Required Required
Not allowed Allowed
Not allowed Not allowed
x8 slot x16 slot
Required Required
Allowed Allowed
Required Allowed
Not allowed Required
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