Help Me Choose: RAID

 

Understanding RAID
RAID or Redundant Array of Independent (or Inexpensive) Disks, is a way of storing data on many independent physical disks for the purpose of enhanced performance and/or fault tolerance.

There are several different RAID types or levels that determine how the data is stored. Each RAID level has specific data protection and system performance characteristics. The following are commonly used RAID levels:

  • RAID 0 — Striping without parity, improved performance, additional storage, no fault tolerance
  • RAID 1 — Mirroring without parity, fault tolerance for disk errors and single disk failures. Minimum number of drives: 2
  • RAID 5 — Striping with distributed parity, improved performance, fault tolerance for disk errors and single disk failures. Minimum number of drives: 3
  • RAID 6 — Striping with dual parity, fault tolerance for dual drive failures. Minimum number of drives: 4
  • RAID 10 — Mirroring combined with striping, better performance, fault tolerance for disk errors and multiple drive failure (one drive failure per mirror set). Minimum number of drives: 4
  • RAID 50 — Combines multiple RAID-5 sets with striping, improved performance, fault disk errors and multiple drive failures (one drive failure per span). Minimum number of drives: 6
  • RAID 60 — Combines multiple RAID-6 sets with striping, improved performance, fault disk errors and multiple drive failures (two drive failures per span). Minimum number of drives: 8

Selecting the RAID That Is Right for You

PERC S100: Entry RAID, ideal for Windows® customers who want to use up to four SATA HDD or SSD devices in a cabled configuration and want a no-cost RAID option for RAID 0, 1, 5 and 10.

PERC S300: Value RAID, ideal for Windows customers who want to use up to eight SAS or SATA HDD’s in a cabled or hot-plug configuration and want an affordable RAID option for RAID 5 and 10.

SAS 6/IR: Value RAID controller required for customers who use Linux® OS or any virtualization OS (Hyper-V™, VMware® ESX, XenServer™) and require RAID 0, 1 or SAS non-RAID configuration.

PERC 6/I:
  • Premium RAID controller available for customers who use Windows or Linux OS or any Virtualization OS (Hyper-V, VMware ESX, XenServer) and need RAID 10, 5, 6 or SAS SSD RAID 0, 1 configuration
  • Ideal for customers looking for battery-backed write cache and more reliable performance, regardless of OS or RAID level
 
CategorySupported Configuration 
PERC S100
Entry (SATA) SW RAID
OS Support: Windows only. No Virtualization OS Support. Up to 4 drives — SATA HDD or SSD cabled hard drives configurations only. RAID levels: 0, 1, 5, 10
PERC S300
Value (SAS/SATA) SW RAID
OS Support: Windows only. No Virtualization OS Support. Up to 8 drives — SAS or SATA HDD cabled or hot-plug hard drives. RAID levels: 0, 1, 5, 10
SAS 6/IR
Value (SAS/SATA) HW RAID
OS Support: Windows, Linux and Virtualization OS support. Up to 8 drives — SAS or SATA HDD cabled or hot-plug hard drives. RAID levels: 0, 1
PERC 6/I
Premium (SAS/SATA) HW RAID
OS Support: Windows, Linux and Virtualization OS support. Up to 16 drives — SAS HDD/SSD or SATA HDD/SSD cabled or hot-plug hard drives. With battery-backed write cache. RAID levels: 0, 1, 10, 5, 50, 6, 60
 

Advantages of RAID
Depending on how you implement RAID, the benefits include one or both of the following:

  • Faster performance: In RAID 0, 10, 50 or 60 virtual disks, the host system can access simultaneously. This improves performance because each disk in a virtual disk has to handle the request. For example, in a two-disk virtual disk, each disk needs to provide only its requested data.
  • Data protection: In RAID 1, 10, 5, 6, 50 and 60 virtual disks, the data is backed up on disk (mirror). In the RAID 5, 50, 6 or 60 virtual disks, the data is parity protected on a single multiple disks. RAID 10, 50 and 60 also allow the host to access disks simultaneously.