MFT Raid Net Storage Yields
Buying four 32 gigabyte drives will not give you 128 gigabytes of storage. Rather, your usable storage will be determined by the RAID configuration you choose (if any) as well as other factors. The two principal factors here are first that what flash drive manufacturers deliver is not gigabytes but rather billions of bytes. Thus, a "32 gigabyte" drive has 32 billion bytes. The second is that our technology recommends a ten percent physical space reserve, reducing a 32 billion byte drive to approximately 28.8 billion bytes. To help you with drive count specification, we have prepared RAID tables that show you net space yields for different counts of drives. All values, as with the bare drives themselves, are expressed in billions of bytes:
RAID-5 Net Gigabytes of Space |
Drive Count |
|
3 |
4 |
6 |
8 |
10 |
12 |
14 |
16 |
32gb drive |
57.6 |
86.4 |
144.0 |
201.6 |
259.2 |
316.8 |
374.4 |
432.0 |
64gb drive |
115.2 |
172.8 |
288.0 |
403.2 |
518.4 |
633.6 |
748.8 |
864.0 |
128gb drive |
230.4 |
345.6 |
576.0 |
806.4 |
1,036.8 |
1,267.2 |
1,497.6 |
1,728.0 |
Within the MFT environment, RAID-5 generally offers the most efficient balance between total performance and storage capacity. The reason is because the linear writes of MFT obviate the need for random reading all drives for each individual update. Instead, updates are aggregately read and parity is aggregately calculated for each stripe. As such, RAID-5 offers a lot more bang-per-buck than does RAID-10 when used with MFT.
RAID-0 Striped-Only Net Gigabytes of Space |
Drive Count |
|
1 |
2 |
4 |
6 |
8 |
10 |
12 |
14 |
16 |
32gb drive |
28.8 |
57.6 |
115.2 |
172.8 |
230.4 |
288.0 |
345.6 |
403.2 |
460.8 |
64gb drive |
57.6 |
115.2 |
230.4 |
345.6 |
460.8 |
576.0 |
691.2 |
806.4 |
921.6 |
128gb drive |
115.2 |
230.4 |
460.8 |
691.2 |
921.6 |
1,152.0 |
1,382.4 |
1,612.8 |
1,843.2 |
In addition to either RAID-5 or RAID-0, you are, of course, welcome to also use no RAID at all. However, this may provide less than adequate protection for your data.