RAID Controllers

About hardware RAID controllers

Hardware RAID for Dell PowerEdge and HPE ProLiant servers: PERC and Smart Array controllers alongside servers supplied with a controller fitted, plus a plain guide to choosing a RAID level. Stocked in Doha.

A hardware RAID controller manages a server's drives as protected arrays, so a single drive failure does not take data or services offline. This collection gathers Dell PERC and HPE Smart Array controllers alongside Dell PowerEdge and HPE ProLiant servers that ship with a controller already fitted.

It is for buyers deciding how to protect their data: choosing a RAID level, weighing hardware against software RAID, or sizing an array before ordering drives. For controller formats, cache and cabling, see the RAID controller cards guide.

1-1_HPE Smart Array P440ar RAID Controller DL360 Gen9.png
RAID levels
0, 1, 5, 6, 10
Drive interfaces
SAS, SATA
Vendors
Dell, HPE

RAID levels compared

LevelMinimum drivesSurvivesUsable capacitySuits
RAID 02No drive failuresAll drivesScratch space only
RAID 12One drive failureHalfOperating system and boot volumes
RAID 53One drive failureAll but one driveRead-heavy file and application storage
RAID 64Two drive failuresAll but two drivesLarge-capacity arrays
RAID 104One drive per mirrored pairHalfDatabases and virtualisation

Hardware RAID or software RAID

Hardware RAID moves parity work onto the controller, protects in-flight writes with a battery- or flash-backed cache, and presents a single volume that any operating system can boot from. Software RAID, such as Windows Storage Spaces, Linux mdadm or ZFS, needs no special card and is not tied to one controller, but it uses host processor time and needs the drives presented directly, for example through a controller in HBA mode.

VMware ESXi hosts with local disks normally rely on hardware RAID, while ZFS and other software-defined storage expect direct access to each drive.

Before you build an array

  • Use drives of the same type, size and speed in one array. See Hard Drives.
  • Large hard drives take a long time to rebuild, so RAID 6 is the safer choice for big arrays.
  • Keep a hot spare in larger arrays so a rebuild starts without waiting for a visit.
  • Check the cache battery. A failed one quietly slows every write. Replacements are in RAID Batteries.
  • RAID keeps a server running through a drive failure. It is not a backup.

ServerDove can set up the array as part of its base configuration service before the server leaves Doha, and quote for complete servers built around your storage plan.

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