Nope, only one drive. Assuming you have 3 drives, it works on the principle A(xor)B=C, where A and B are actual data on two of the drives and C is the checksum. So if one drive fails you either have A and B, A and C (B=C(xor)A) or B and C (A=C(xor)B ).The data on the three drives is laid out as follows:Originally posted by muchspl2@11 August 2004 - 05:24
herd good things about raid 5
my next system will be it
form what I understand if one drive fails you can fix it & even if 2 drives fail you can fix it
ABC
CAB
BCA
ABC
etc, so that when a drive fails it only has to do the calculation to recover the lost data once in every three reads on average. Obviously there is a slight performance hit, but not too bad.
With some systems you can even replace the drive without shutting the system down (hot swapping), but even if that's not possible you only have to be down for the few minutes it takes to physically replace the drive, and can then build the raid structure while the system is running.
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