Preface - nStor Corporation Ultra S2S User Manual

Preface

Congratulations on the purchase of your new Ultra S2S RAID Controller from
nStor Corporation. The Ultra S2S RAID Controller brings high-performance
transfer rates and fault-tolerant RAID operations in an Ultra SCSI environment
to the nStor CR8e disk array subsystem attached to any computing platform
equipped with a standard Ultra SCSI host adapter. The Ultra S2S RAID
Controller is a intelligent caching controller that supports standard RAID levels:
0, 1, 0+1, 3, and 5 for multiple-drive arrays, and JBOD (just a bunch of drives)
for single drive control.
This generation of RAID controller allows continuous access to data in the event
of a disk drive failure. It also provides continuous access to the data in the event
of a controller failure and this capability is achieved with a dual-active controller
system which uses two Ultra S2S RAID Controllers sharing access to the same
array of disk drives. In the event of one controller failure, operations are assumed
by the surviving controller through a process called fail-over. Once the failed
controller is replaced, the new controller resumes processing array operations in a
fail-back process. During fail-over and fail-back, write cache coherency is
maintained within the disk drives.
New product enhancements include online RAID expansion (MORE ™ ) which
allows the addition of one or more drives to a RAID set while the controller is
online with the host system. Also, depending upon the choice of RAID
configurations, the Ultra S2S RAID Controller appears to the operating system as
one or more logical units, allowing maximized application performance.
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