Hardware RAID vs software RAID

Hardware RAID and software RAID both combine drives into one volume, and differ in where the mirroring and parity work runs. Hardware RAID runs it on a controller card, such as a Broadcom MegaRAID adapter, with its own processor and cache. Software RAID runs it on the host CPU inside the operating system, as Linux md (managed with mdadm) and Windows Storage Spaces do.

Broadcom's MegaRAID 9560-16i carries 8 GB of cache, protected by the CVPM05 CacheVault supercapacitor module. The 9560-8i carries 4 GB. Broadcom rates CacheVault data retention at 3 years or more, against up to 72 hours for older battery units. Linux md has no card cache, but for RAID 4, 5 and 6 it can use a journal device, and the kernel documentation warns that a dirty, degraded RAID 5 or 6 array can hide data corruption. Microsoft describes Storage Spaces as pooling drives into virtual disks with simple, mirror and parity layouts.

Pick hardware RAID when the array needs a protected write cache and vendor tooling. Pick software RAID when the drives are NVMe and the CPU has headroom. Either way, keep a separate backup.

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Last verified October 30, 2026.