RAID level-1:
RAID level-1 provides 100% data
redundancy and requires two hard disk drives. With RAID
level-1, the first half of a stripe is the original data; the
second half of a stripe is a
mirror (copy) of the data, but
written to another drive.
Because the data is mirrored, the capacity of the logical
drive when assigned RAID level-1 is 50% of the physical
capacity of the two hard disk drives in the array.
The following illustration shows data arranged in an array
of two hard disk drives defined as one RAID level-1 logical
drive. Notice that the data on Drive B is a mirror copy of
the data on Drive A.
If one of the hard disk drives fails, the ServeRAID
controller switches read and write requests to the
remaining functional drive in the array.
Enhanced RAID level-1:
When you group more than
two physical drives into an array and select RAID level-1,
the ServeRAID controller automatically assigns the IBM
Enhanced RAID level-1 to the array.
The Enhanced RAID level-1 combines mirroring with data
striping. This RAID level stripes data and copies of the
data across all the drives in the array. As with the
standard RAID level-1, the data is mirrored, and the
capacity of the logical drive is 50% of the physical capacity
of the grouping of hard disk drives in the array.
The Enhanced RAID level-1 requires a minimum of three
drives and, depending upon the stripe-unit size, supports a
maximum of eight or 16 drives.
The following illustration shows data arranged in an array
with three hard disk drives. The logical drive is assigned
the Enhanced RAID level-1. Notice that the first stripe is
the data stripe and the second stripe is the mirror (copy) of
the first data stripe, but shifted one drive.
Drive A
.
.
Drive B
.
.
Data Stripe 1
Block 1
Mirror Stripe
1
Block 1
Data Stripe 2
Block 2
Mirror Stripe
2
Block 2
Data Stripe 3
Block 3
Mirror Stripe
3
Block 3
Netfinity 5500 M20 - Type 8662
69
Summary of Contents for 866251Y - Netfinity 5500 M20
Page 2: ......
Page 8: ...vi Netfinity Server HMM...
Page 336: ...32 33 33 34 35 36 37 38 39 40 41 42 43 328 Netfinity Server HMM...
Page 346: ...338 Netfinity Server HMM...
Page 354: ...346 Netfinity Server HMM...
Page 355: ...Related service information 347...
Page 356: ...348 Netfinity Server HMM...
Page 357: ...Related service information 349...
Page 368: ...360 Netfinity Server HMM...
Page 369: ...Related service information 361...
Page 385: ......
Page 386: ...IBM Part Number 09N1015 Printed in U S A S37L 2 2 1...
