CalDigit T3: 3-HDD RAID-1 Mirror

A RAID-1 mirror replicates the data across N drives (N = 3 here) for fault tolerance: in a mirror, N-1 of N drive can fail with no loss of data or functionality.

For reads with a RAID-1 mirror, there is potential to read from more than one drive, thus enhancing read performance. It is never as as good as RAID-0 striping because the reads are offset (staggered) among the drive members of the mirror, but an optimized controller or driver can extract some benefits.

Results

Tested with three fast Toshiba 7200 rpm DT01ACA200 series drives using SoftRAID 5 with reads from all drives enabled.

MB/sec:
Single drive: 184 write / 181 read
2-drive mirror: 184 write / 198 read
3-drive mirror: 184 write / 271 read

CalDigit has three SATA controllers in the T3, and this apparently pays off by delivering 178 MB/sec writes speed (single drive speed), and 274 MB/sec read speed, which is about 54% faster than the ~1804MB/sec speed of a single drive used here. It’s a far cry from the theoretical 3X speed that a sophisticated hardware controller could in theory obtain, but here at MPG we have yet to see such a device.

Bottom line: a triple RAID-1 mirror in the CalDigit T3 delivers outstanding fault tolerance along with read speed sufficient for the vast majority of computing tasks.

Write speeds are in gray and are identical whether it is a single drive or a 2-drive or 3-drive mirror—this is as expected.

CalDigit T3 Thunderbolt: RAID-1 mirror speed (2 and 3 drives) vs single drive