IBM DS8880 Series, Introduction And Planning Manual

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RAID implementation provides fault-tolerant data storage by storing the data in
different places on multiple drives. By placing data on multiple drives, I/O
operations can overlap in a balanced way to improve the basic reliability and
performance of the attached storage devices.
Physical capacity for the storage system can be configured as RAID 5, RAID 6, or
RAID 10. RAID 5 can offer excellent performance for some applications, while
RAID 10 can offer better performance for selected applications, in particular, high
random, write content applications in the open systems environment. RAID 6
increases data protection by adding an extra layer of parity over the RAID 5
implementation.
RAID 6 is the recommended and default RAID type for all drives over 1 TB. RAID
6 and RAID 10 are the only supported RAID types for 3.8 TB Flash Tier 1 drives.
RAID 6 is the only supported RAID type for 7.6 TB Flash Tier 2 drives.
RAID 5 overview
RAID 5 is a method of spreading volume data across multiple drives.
RAID 5 increases performance by supporting concurrent accesses to the multiple
drives within each logical volume. Data protection is provided by parity, which is
stored throughout the drives in the array. If a drive fails, the data on that drive can
be restored using all the other drives in the array along with the parity bits that
were created when the data was stored.
RAID 5 is not supported for drives larger than 1 TB and requires a request for
price quote (RPQ). For information, contact your sales representative.
Note:
RAID 6 is the recommended and default RAID type for all drives over 1 TB.
RAID 6 and RAID 10 are the only supported RAID types for 3.8 TB Flash Tier 1
drives. RAID 6 is the only supported RAID type for 7.6 TB Flash Tier 2 drives.
RAID 6 overview
RAID 6 is a method of increasing the data protection of arrays with volume data
spread across multiple disk drives.
RAID 6 increases data protection by adding an extra layer of parity over the RAID
5 implementation. By adding this protection, RAID 6 can restore data from an
array with up to two failed drives. The calculation and storage of extra parity
slightly reduces the capacity and performance compared to a RAID 5 array.
The default RAID type for all drives over 1 TB is RAID 6. RAID 6 and RAID 10
are the only supported RAID types for 3.8 TB Flash Tier 1 drives. RAID 6 is the
only supported RAID type for 7.6 TB Flash Tier 2 drives.
RAID 10 overview
RAID 10 provides high availability by combining features of RAID 0 and RAID 1.
RAID 0 increases performance by striping volume data across multiple disk drives.
RAID 1 provides disk mirroring, which duplicates data between two disk drives.
By combining the features of RAID 0 and RAID 1, RAID 10 provides a second
optimization for fault tolerance.
RAID 10 implementation provides data mirroring from one disk drive to another
disk drive. RAID 10 stripes data across half of the disk drives in the RAID 10
configuration. The other half of the array mirrors the first set of disk drives. Access
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DS8880 Introduction and Planning Guide
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