Technical white paper | HP MSA 1040/2040
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For optimal write performance, parity based disk groups (RAID 5 and RAID 6) should be created with “The Power of 2”
method. This method means that the number of data (non-parity) drives contained in a disk group should be a power of 2.
See the chart below.
RAID Type Total Drives per Disk
Group
Data Drives Parity Drives
RAID 5 3 2 1
RAID 5 5 4 1
RAID 5 9 8 1
RAID 6 4 2 2
RAID 6 6 4 2
RAID 6 10 8 2
Due to the limitation of Disk Groups in a pool, which is 16, RAID type should be considered when creating new Disk Groups.
For example, instead of creating multiple RAID1 Disk Groups, consider using a larger RAID 10 Disk Group.
Drive Type and Capacity Considerations when using Tiering
All hard disk drives in a tier should be the same type. For example, do not mix 10K RPM and 15K RPM drives in the same
Standard Tier.
If you have a Performance Tier on the MSA 2040, consider sizing the Performance Tier to be 5%-10% the capacity of the
Standard Tier.
Disk Group RAID Type Considerations
RAID 6 is recommended when using large capacity Midline (MDL) SAS drives in the Archive Tier. The added redundancy of
RAID 6 will protect against data loss in the event of a second disk failure with large MDL SAS drives.
RAID 5 is commonly used for the Standard Tier where the disks are smaller and faster resulting in shorter rebuild times.
RAID 5 is used in workloads that typically are both random and sequential in nature.
See the Best practices for SSDs
section for RAID types used in the Performance Tier and Read Cache.
Global Spares with Tiers
Using Global spares is recommended for all tiers based on spinning media. When using these global spares, make sure to
use the same drive types as the Disk Group. The drive size must be equal or larger than the smallest drive in the tier.
Best practices when choosing drives for HP MSA 1040/2040 storage
The characteristics of applications and workloads are important when selecting drive types for the HP MSA 1040/2040 array.
Drive types
The HP MSA 1040 array supports SAS Enterprise drives and SAS Midline (MDL) drives. The HP MSA 2040 array supports SSDs,
SAS Enterprise drives, SAS Midline (MDL) drives, and Self-Encrypting Drives (SED). See the Full Disk Encryption
section below
for more information on SED drives. The HP MSA 1040/2040 array does not support Serial ATA (SATA) drives. Choosing the
correct drive type is important; drive types should be selected based on the workload and performance requirements of the
volumes that will be serviced by the storage system. For sequential workloads, SAS Enterprise drives or SAS MDL drives
provide a good price-for-performance tradeoff over SSDs. If more capacity is needed in your sequential environment, SAS
MDL drives are recommended. SAS Enterprise drives offer higher performance than SAS MDL and should also be considered
for random workloads when performance is a premium. For high performance random workloads, SSDs would be
appropriate when using the MSA 2040 array.
SAS MDL drives are not recommended for constant high workload applications. SAS MDL drives are intended for archival
purposes.
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