Promise Technology Pegasus3 R4, Product Manual, Page: 178 / 232

165
Technology Background Pegasus3 Product Manual
Advantages Disadvantages
• Simplest RAID level
• Can increase read performance by
processing data requests in parallel
since the same data resides on two
different drives
• Very high disk overhead – uses only 50% of
total capacity
Recommended Applications for RAID 1:
• Accounting
• Payroll
• Financial
• Any application requiring very high availability
RAID 1E – Enhanced Mirror
RAID 1E offers the security of mirrored data provided by RAID 1 plus the added capacity of more than
two physical drives. It also offers overall increased read/write performance plus the flexibility of using an
odd number of physical drives. With RAID 1E, each data stripe is mirrored onto two physical drives. If
one drive fails or has errors, the other drives continue to function, providing fault tolerance.
RAID 1E can mirror data over an odd number of drives
The advantage of RAID 1E is the ability to use an odd number of physical drives, unlike RAID 1
and RAID 10. You can also create a RAID 1E Logical Drive with an even number of physical drives.
However, with an even number of drives, you obtain somewhat greater security with comparable
performance using RAID 10.
RAID 1E logical drives consist of three or more physical drives. You can create an array with just two
physical drives and specify RAID 1E. But the resulting array is actually a RAID 1.
Physical Drives
Enhanced Data Mirrors