Chapter4.SystemAvailability
The IBM S/390 Integrated Server offers improved system reliability when compared
to an average 43x1, 937x, or 922x. When compared to the older machine's system
configuration, including attached DASD and DASD controllers, the S/390 Integrated
Server hardware reliability of mean time between failure can be 2 to 5 times better.
Using RAID configurations yields even better results when you look at overall
availability.
DASD/DiskStorage
The IBM S/390 Integrated Server has up to 255GB of usable DASD internal to the
system. The sixteen internal hot-swappable hard disk drives in a RAID 5
configuration allows for the replacement of the failing drive without shutting down
the system.The unique
cooling design promotes maximum airflow over system
components and all disk drives for system cooling and reliability.By
reducing the
hardware complexity and points of failure,
and by providing hot-swappable disk
drives, the IBM S/390 Integrated Server is designed for superior system availability.
RAID
The IBM S/390 Integrated Server model supports a RAID 5 configuration.With
RAID 5, sectors that comprise a logical drive are striped across each of the hard
drives in the array intermixed with parity data.In the case of disk failure,
the
system uses the encoded data from the surviving disks to reconstruct the lost data
“on the fly.” The failed disk can be replaced and automatically reconstructed during
background processing on a standby disk.RAID 5provides ease of configuration
since data is spread across every disk.The RAID drives therefore appear to be
one or a small number of large disk drives, rather than many small drives, making
the configuration easier to manage.
PowerManagement
To improve the system availability, an optional Internal Battery Feature (IBF) is
available. The IBF protects the system from utility outages, which may be
prevalent in certain geographic regions.By
providing the IBF, the system remains
powered up during the outage, thus allowing for an orderly shutdown in the event of
extended outages, and ensuring data integrity for S/390 applications.
| The power subsystem is designed with N+1 redundancy.Failure of a power
| thermal component does not cause a system outage.This allows for concurrent
| replacement of a failed power subsystem component.The power system offers
| dual primary (AC) power feeds.Each feed is electrically isolated to enable
| redundant power paths.
 Copyright IBM Corp. 1998 9