Re: raid5 resize in 2.6.17 - how will it be different from raidreconf?

[Dexter Filmore <Dexter.Filmore@gmx.de>]

> > Will it be less risky to grow an array that way?
>
> It should be.  In particular it will survive an unexpected reboot (as
> long as you don't lose and drives at the same time) which I don't
> think raidreconf would.
> Testing results so far are quite positive.

Write cache comes to mind - did you test power fail scenarios?

> > (And while talking of that: can I add for example two disks and grow
> > *and* migrate to raid6 in one sweep or will I have to go raid6 and then
> > add more disks?)
>
> Adding two disks would be the preferred way to do it.
> Add only one disk and going to raid6 is problematic because the
> reshape process will be over-writing live data the whole time, making
> crash protection quite expensive.
> By contrast, when you are expanding the size of the array, after the
> first few stripes you are writing to an area of the drives where there
> is no live data.

Let me see if I got this right: if I add *two* disks and go from raid 5 to 6 
with raidreconf, no live data needs to be overwritten and in case something 
fails I will still be able to assemble the "old" array..?


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