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Why Use Software RAID?
Hardware RAID has long been used in industry for applications where fault tolerance is critical. Such solutions can be expensive, albeit sometimes obtuse and designed for knowledgeable users.
Hardware RAID has various downsides and upsides:
- Expense: 4+ drive hardware RAID tends to be expensive.
- Limited choice: often restricted in size or capacity of drives.
- Obtuse: the hardware RAID may require special configuration software to be learned for that particular solution and hardware.
- Choices tend to be limited, and specialized software might be required.
- Specialized hardware might be required (e.g., PCIe card).
- Performance is not necessarily best.
- Plus: Multiple power supplies, hot spares, etc: can auto-recover if other components fail with no user interventions.
- Plus: more advanced RAID options, like RAID-6 (dual redundancy).
Truly mission critical systems need things like redundant power supplies and hot spares, so there is plenty of space for hardware-based RAID. And for simple RAID-1 mirror, a dual drive hardware RAID can also be attractive.
With the advent of Thunderbolt-based multi-drive solutions and the emergence of software RAID in SoftRAID 5 for OS X, software RAID offers high performance and flexible RAID options at little more than the cost of off the shelf hardware:
- Very high performance for all RAID types including impressive features like fast mirror rebuilds.
- Cost only modestly more than non-RAID hardware.
- Mix RAID with non-RAID or types of RAID in the same box and/or add drives later in another enclosure—not limited to one enclosure!
- Flexible choice of hardware, compatibility across Macs (unplug and replug in another, it just works).
- Excellent integration with OS X including alerts and email; friendly software that can be used with any hardware—learn it once.
The choice of RAID type, the ability to quickly and easily tailor volume size and characteristics are all highly attractive, as shown below (mouse over to see various choices).