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Re: backup archive format saved to disk



Ron Johnson wrote:

[snip]


What your code looks like is RAID-3.

http://en.wikipedia.org/wiki/RAID#RAID_3

    A RAID 3 uses byte-level striping with a dedicated
    parity disk. RAID 3 is very rare in practice. One
    of the side-effects of RAID 3 is that it generally
    cannot service multiple requests simultaneously. This
    comes about because any single block of data will, by
    definition, be spread across all members of the set
    and will reside in the same location. So, any I/O
    operation requires activity on every disk.

[snip]

Ok, fair enough. But I didn't do any striping.

What you've done is create a parity disk.  Useful, but not
RAID.

Pardon? Perhaps you are using a definition of RAID I'm not familiar with. "Redundant Array of Inexpensive Discs" (some have
changed that to "Independent".)

I'll admit that this is not the usual way it is implemented, but
it is certainly RAID to my way of thinking, and conforms to the definitions I've seen, and uses the same kind of redundant data.


Integral to the implementation of RAID is that the disk is divided
into large blocks, and there are parity blocks for data blocks.

I don't like arguments. That isn't what I've been led to believe.
Raid 1 doesn't do that, AFAIK. I won't respond further, as this
is getting way away from the OPs question.

Mike
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