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RAID Support Overview

Both software and hardware RAID support are available in ClearOS. If you plan on implementing hardware RAID, please read the section below regarding supported hardware. Before you decide to purchase an expensive hardware RAID controller card, consider the following passage from the experts at O'Reilly:

“Software RAID has unfortunately fallen victim to a FUD (fear, uncertainty, doubt) campaign in the system administrator community. I can’t count the number of system administrators whom I’ve heard completely disparage all forms of software RAID, irrespective of platform. Many of these same people have admittedly not used software RAID in several years, if at all.

“Why the stigma? Well, there are a couple of reasons. For one, when software RAID first saw the light of day, computers were still slow and expensive (at least by today’s standards). Offloading a high-performance task like RAID I/O onto a CPU that was likely already heavily overused meant that performing fundamental tasks such as file operations required a tremendous amount of CPU overhead. (…) But today, even multiprocessor systems are both inexpensive and common.” - Derek Vadala - Managing RAID on Linux - O'Reilly

Software RAID Support

You can implement software RAID in ClearOS by selecting the Create Custom Layout option in the installation wizard. You can find tips and tricks about partitioning in the section Configuring Partitions and RAID.

Hardware RAID Support

Some hardware RAID controller cards are not true hardware controller cards. They are simple hard disk controllers with BIOS and drivers to do software RAID Support. If redundancy is your primary concern, then software RAID will serve you better than a quasi-hardware RAID support card. To quote (again) from the Managing RAID on Linux book from O'Reilly:

“The low-end (RAID) controllers are, in essence, software RAID support controllers because they rely on the operating system to handle RAID support operations and because they store array configuration information on individual component disk. The real value of the controller is in the extra ATA channels.”

Supported hardware RAID cards:

  • Adaptec SCSI - 200x, 21xx, 22xx, 27xx, 28xx, 29xx, 32xx, 34xx, 39xx, 54xx
  • Adaptec IDE - 2400A
  • 3ware IDE - Escalade 3W 5xxx/6xxx/7xxx
  • MegaRAID SAS 9240-4i
  • MegaRAID SAS 9240-8i
  • MegaRAID SAS 9260-4i
  • MegaRAID SAS 9260-8i
  • MegaRAID SAS 9260DE-8i
  • MegaRAID SAS 9261-8i
  • MegaRAID SAS 9280-8e
  • MegaRAID SAS 9280DE-8e
  • MegaRAID SAS 9280DE-8e
  • MegaRAID SAS 9280-24i4e
  • MegaRAID SAS 9280-16i4e
  • MegaRAID SAS 9280-16i
  • MegaRAID SAS 8704ELP
  • MegaRAID SAS 8704EM2
  • MegaRAID SAS 8708ELP
  • MegaRAID SAS 8708EM2
  • MegaRAID SAS 8880EM2
  • MegaRAID SAS 8888ELP

Unsupported, but may work:

Unsupported and not recommended:

  • Most Promise hardware, notably FastTrak100 TX and FastTrak TX2000
  • HighPoint RocketRAID cards

As a rule of thumb, if a hardware card is under USD $150, then it is probably not true hardware RAID and either not recommended or not supported.

content/en_us/6_c_raid_support.txt · Last modified: 2015/08/13 16:31 (external edit)