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Promise
Technology
Pegasus3 R4/R6/R8
RAID 1 – Mirror
When a logical drive is mirrored, identical data is written to a pair of physical drives, while reads are
performed in parallel. The reads are performed using elevator seek and load balancing techniques
where the workload is distributed in the most efficient manner. Whichever drive is not busy and is
positioned closer to the data is accessed first.
With RAID 1, if one physical drive fails or has errors, the other mirrored physical drive continues to
function. Moreover, if a spare physical drive is present, the spare drive is used as the replacement drive
and data begins to mirrored to it from the remaining good drive.
RAID 1 Mirrors identical data to two drives
The logical drive’s data capacity equals the smaller physical drive. For example, a 100 GB physical
drive and a 120 GB physical drive have a combined capacity of 100 GB in a mirrored logical drive.
If physical drives of different capacities are used, there is unused capacity on the larger drive.
RAID 1 logical drives on Pegasus consist of two physical drives.
If you want a mirrored logical drive with more than two physical drives, see “RAID 1E – Enhanced
Physical Drives
Data Mirror
Summary of Contents for Pegasus3 R4
Page 4: ...iv Promise Technology Pegasus3 R4 R6 R8 VCCI KCC FCC ...
Page 5: ...v About this guide Pegasus3 Product Manual WARNING WARNING WARNING WARNING ...
Page 80: ...67 Managing the Pegasus3 Pegasus3 Product Manual Controller Settings ...
Page 207: ...194 Promise Technology Pegasus3 R4 R6 R8 View NVRAM Events ...