Re: databases and RAID ...

Tom Lane writes:

> Is there any rhyme or reason to the various "RAID n" designations?
> Or were they just invented on the spur of the moment?

The paper that introduced the term RAID used a numerical classification
for the various schemes.  (So I guess the answer is yes.)  The traditional
levels are:

0  Nonredundant
1  Mirrored
2  Memory-style ECC
3  Bit-interleaved parity
4  Block-interleaved parity
5  Block-interleaved distributed parity
[Hennessy & Patterson]

There are also other levels.  One poster talked about RAID 10 which
appears to be a mirrored RAID 5.

--
Peter Eisentraut   peter_e@gmx.net