HP LH4r HP NetServer FCArray Assistant - Installation and User Guide - Page 156
Logical Drive States, Logical Drives, Logical Unit Number LUN
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Appendix B Glossary assignments are per host port and are independent of the assignments on other host ports. Logical drives may be assigned only one LUN per host port. By not assigning a LUN to a logical drive on a particular host port, that logical drive is made inaccessible to that host port. Logical Drive States The state of a logical (system) drive can be either ONLINE, CRITICAL, or OFFLINE. Notice that the same term "online" is used for both physical and logical drives. Online: A Logical Drive is in an "online" state if... All of its member drives are "online." Critical: A Logical Drive is in a "critical" state if... It has been configured at RAID level 1, 3, 5, or 0+1; and One (and only one) of its member drives is not "online." A logical drive is considered "critical" because any failure of another of its member drives may result in a loss of data. I/O operation can only be performed with logical drives that are online or critical. Offline: A Logical Drive is in an "offline" state if... No data can be read from it or written to it. System commands issued to offline logical drives are returned with an error status: no operations can be performed on offline logical drives. A logical drive can be "offline" under one of two situations described below: ◊ It is configured with a redundant RAID level (1, 3, 5, or 0+1) and two or more of its member drives are not "online"; or ◊ It is configured at RAID level 0 or JBOD, and one or more of its member drives are not "online." Logical Drives A logical drive is equivalent to a "system" drive. Logical drives are presented to the operating system as available disk drives, each with a capacity specified by the disk array controller. Logical Unit Number (LUN) A SCSI representation of a system drive (logical drive) on a given channel and target ID. 150