To remove an EMU, loosen the small thumbscrews at each end and then remove the EMU by pulling it out from the enclosure. To install one, slide the EMU into the enclosure until it stops and tighten the thumbscrew until secure. To maintain optimum cooling, avoid operating a SANnet II 200 SCSI array for more than a few minutes with an EMU removed.
SCSI Module
The SCSI connections to hosts and between enclosures are made at the SCSI modules (i.e., I/O modules). This hot-serviceable module is used to select between split-bus and single-bus disk mid-plane configurations using the SCSI bus configuration cable. The SCSI modules also contain the actual SAF-TE circuitry the EMUs communicate with.
Each SCSI port features a very high-density (VHD) interface with automatic SCSI termination, where needed. To remove a SCSI module, loosen the large thumbscrews at each end and then remove the SCSI module by pulling it out from the enclosure. SCSI modules differ between base enclosures and expansion enclosures.
FIGURE 9: SCSI Module (i.e., I/O Module)
The SCSI channels of base enclosures can be set for use with disks or hosts by the controllers, and expansion enclosures can be used as stand-alone storage systems with host-based volume management software, so the numerous possible methods of connecting hosts and interconnecting enclosures is beyond the scope of this document. Consult the SANnet II 200 SCSI array user’s guide for more detailed information.
A SANnet II 200 SCSI array SCSI module is hot-serviceable, but not hot-swappable, so replacing one will require planned downtime. To remove a SCSI module, loosen the large thumbscrews at each end and then remove it by pulling it out from the enclosure. To install one, slide the SCSI module into the enclosure until it stops and tighten the thumbscrew until secure. When replacing SCSI modules, move the SCSI cables from the original SCSI module to the equivalent SCSI ports of the new SCSI module after the replacement for best results.
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