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RTM-ATCA-SXXX Overview
6806800H62B ATCA‐S201InstallationandUseGuide60
5.2.1 Hardware RAID levels and capabilities
RAID Level
RAID0 RAID1 RAID1E
Description
Two or more disks are
grouped to provide a
capacity aggregation
function. The advantage is
the multiplicative
performance and capacity
effect of up to 10 spindles
working in concert to store
or retrieve data for the host.
Exactly two disks are grouped
to provide a mirror function.
By definition, two drives our
bounded in a fashion such
that every write to one drive
is mirrored to the second. If a
failure occurs with either
drive, data is still accessible
via the surviving drive.
Three or more disks are grouped to
provide a mirror function using an
algorithm extension to permit use
with many drives. If a failure occurs
with any drive, data is still accessible
via the surviving drives.
Data
Layout
Diagram
Disk 1
Disk 2
S0 S1
S2 S3
S4 S4
Stripe
Stripe
Stripe
S0
S1
S2
S3
S4
Data
RAID0
Disk 1
Disk 2
S0 S0’
S1 S1’
S2 S2’
Stripe
Stripe
Stripe
RAID1
S0
S1
S2
S3
S4
Data
Disk 1
Disk 2
S0 S0’
S1’ S2
S3 S3’
Stripe
Stripe
Stripe
RAID1E
Disk 3
S1
S2’
S4
S0
S1
S2
S3
S4
Data
Important considerations and volume restrictions
1. A maximum of 2 RAID volumes may be defined on each ATCA-S201.
2. A maximum of 2 global hot spares may be defined for each ATCA-S201.
3. A maximum of 10 disks may be used for a single RAID volume
4. A maximum of 12 disks (cumulative) for both RAID volumes (not including
spares)
5.2.2 How new RAID definitions alter device menu display
The number of devices appearing in the Physical Disks menu will change once the
user applies RAID services. The figure below illustrates this concept. In this
example, there are four AMC disk modules available to the ATCA-S201, but only
three disks appear in the physical disk menu.