HP 3000 Manuals HP 3000 Manuals
Chapter 2 SYSTEM INFORMATION Introducing Mirrored Disk/XL by Kendall Sutton Commercial Systems Division Hewlett-Packard is pleased to introduce a new product, Mirrored Disk/XL. Mirrored Disk/XL features the ability to maintain two copies of all data residing on a non-system volume set. Two physical disks comprise each volume of the mirrored volume set, providing transparent protection against disk failures as well as the ability to perform backup while applications are accessing the data. PRODUCT FEATURES Mirrored Disk/XL provides the following features: * Protection against disk failures * Online disk backup * User transparency Protection Against Disk Failures Mirrored Disk/XL protects against down time due to disk drive failure by providing redundant or mirrored drives for critical application data. In the event of a failure of a disk that is mirrored, all I/O activity for the mirrored pair is automatically switched to the partner disk. Repair and resynchronization of the failed disk are performed online with no interruption in application processing. Online Backup Mirrored Disk/XL features the ability to split mirrored volume sets, allowing half of a set to be used for backup while the other half is available for application processing. Applications are inactivated for a short period of time (approximately five minutes) while the backup is started. Applications can then continue processing throughout the duration of the backup. Mirrored Disk/XL Online Backup is completely integrated with the standard MPE XL backup utility STORE/XL and the product TurboSTORE/XL (HP30319A). Transparent to Applications and Users Mirrored Disk/XL is transparent to application design. No modification of current applications is required to capture the full benefit of Mirrored Disk/XL. Mirrored Disk/XL operation is also transparent to application users. Users are typically unaware that a mirrored disk may have failed or that a failed mirrored disk has been replaced. Supported on All MPE XL Platforms Mirrored Disk/XL is supported on all MPE XL hardware platforms (Release 2.1 or later) and requires disk drives equipped with fiber optic links. For further information refer to the related article in the "Technical Articles" section in this Communicator.