A hot-pluggable PCI (peripheral component interconnect) interface card, which can be removed and inserted without turning off the server, is valuable because it can increase the level of "availability" on a server. Availability is becoming one of the most important attributes of PC servers since the higher the availability, the less potential a server has of being shut down and going off line. Servers that go off line can have an extremely adverse impact on a company-wide network.
Significantly, when Hot-Plug PCI cards are commercialized, two of the most critical plug-in devices in a PC server will be capable of removal and insertion without shutting down the server : the interface cards and storage devices. Storage devices, such as hard disk drives, are already hot-pluggable in high-end servers.
The most common PCI devices currently used in servers include network cards and SCSI and RAID cards which interface with hard disk arrays.
A first draft of the specification has been forwarded to the PCI Hot Plug Workgroup for review. Hot Plug PCI development platforms have also been passed along to third-party hardware developers so work on accompanying software drivers can proceed.
Products based on the spec will let network managers accomplish three things: online replacement of malfunctioning or old PCI connection cards, the ability to upgrade to next-generation PCI products, and the ability to expand existing connections online. With this functionality, Intel-based vendors like Compaq hope to take another step closer to the high-availability features commonly found in Unix and mainframe systems.
Compaq plans to implement Hot PCI Replacement, Hot PCI Upgrade, and Hot PCI Expansion. The technology may be most useful for administrators who must maintain constant access to external disk drive storage for users. Products including the spec are expected to roll out in the first half of next year.
Compaq will come out with a line of new Proliant servers in the first half of 1997 which support the technology, said Carl Walker, director of technology development for enterprise computing at Compaq. These servers will be based on a new Compaq motherboard with logic chips which enable the technology, he said. Other PC server vendors that wish to support Hot Plug PCI must also include these support chips.
However, the use of new PCI devices will not be imperative, Walker said. Older, so-called "legacy" PCI cards will work, he added. Only new new drivers will be necessary, he said.
Compaq will ship the these new drivers with the Proliant servers it plans to ship in the first half of 1997, he said. These drivers will initially work with Windows NT 4.0 but eventually be integrated into Windows NT 5.0, according to Walker.