On Thu, 21 Oct 2004, Gareth Eason wrote:
>> Will it allow you to expand a RAID5 array? If so, it must be doing
> something clever(tm)
Nope. Could be just brute force and tediousness.
In fact it's probably Windows defrag. :-)
Adding a new disk inserts a blank stripe every N stripes. The controller
can simply walk the array start to finish reshuffling stuff back towards
the start. At any given time, the controller knows where it has got to,
so if a requested block is in the "done" part, the controller finds it
using the new geometry; if in the "not-done" part, it uses the old
geometry.
The above is a guess, (the website isn't enlightening), but is there a
particularly clever alternative?
Ronan
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