IP27 is SGI's software architecture name for the system marketed under the names Origin 200, Origin 2000 and Onyx 2. IP27 is a ccNUMA architecture. The Origin 300, Origin 3000, Octane systems are architecturally similar.
IP27 systems are equipped with R10000 processors at clock rates from 180Mhz and R12000 processors at 250MHz. As a rare feature different processors and versions are permitted to be used mixed in a system which makes assembling a system from components or field maintenance drastically easier. The sole restriction is that both processors on a node board have to use the same clock speed.
IP27 systems come with an IOC3 network card on the mainboard; additional IOC3 cards may be present in the system in form of MENET XIO cards or IOC3 PCI cards. Linux supports the IOC3 but performance is rather moderate to say the least.
By standard IP27 systems are equipped with two Qlogic ISP1020 SCSI hostadapter per module. Origin 200 systems have space for 6 3.5″ internal drives on the primary SCSI bus and 2 internal 5.25″ half height or 1 full height device on the second.
IP27 is supported by Linux 2.4 and Linux 2.6. Due to vastly superior properties of Linux 2.6 on such large systems Linux 2.6 is urgently recommended for IP27 systems. Due to the size of typical systems and properties of the IP27 architecture only 64-bit kernels make sense and are supported. Linux 2.6 requires a small patch in addition to the CVS kernel. The patch is available from ftp://ftp.linux-mips.org/pub/linux/mips/people/ralf.