HP StorageWorks MSA2012i HP StorageWorks 2000 Modular Smart Array Reference Gu - Page 305

controller enclosure controller module copy-on-write (COW) CPLD CPU DAS data host An enclosure that contains disk drives and one or two controller modules. See controller module. A FRU that contains: a Storage Controller processor; a Management Controller processor; a SAS expander and Expander Controller processor; management interfaces; a LAN subsystem; cache protected by a capacitor pack and Compact Flash memory; host, expansion, management, and service ports; and midplane connectivity. In a controller enclosure, the upper controller module is designated A and the lower one is designated B. A technique for maintaining a point in time copy of a collection of data by copying only data that is modified after the instant of replicate initiation. The original source data is used to satisfy read requests for both the source data itself and for the unmodified portion of the point in time copy. (SNIA) See also snap pool. Complex programmable logic device. A generic term for an integrated circuit that can be programmed in a laboratory to perform complex functions. Central processing unit. The CPU is where most calculations take place, and the type of CPU in a controller module affects its performance capability. In MSA2000 Family storage systems, CPU is also referred to as the Storage Controller processor or the RAID controller processor. See direct attach storage (DAS). A host that reads/writes data to the storage system. The MSA2012fc or MSA2012sa can be directly connected to multiple data hosts for direct attach storage (DAS). The MSA2012fc or MSA2012i can be connected to multiple data hosts through switches for a storage area network (SAN). Glossary 305