Best strategy to incrementally replace smaller HDDs

["Michał Sawicz" <michal@sawicz.net>]

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Hi all, given the configuration below:
      * 8 x 1TB HDDs
      * 2 x 2TB HDDs

On which I currently have:
      * (10 x 1TB) RAID6 - persistent storage
      * (2 x 1TB) system / temporary storage etc.

I want to replace the 1TB drives for 2TB ones on an as-needed basis,
what strategy would you recommend?

     1. If I moved to 2TB RAID6 members (using RAID0 on the 1TB drives),
        I would need to replace two of the drives just to match current
        capacity. Each next 2TB drive would get me 1TB additional
        capacity (but actually I'd need to replace two to gain
        anything). That sounds to be most future-proof, but most
        expensive.
     2. If I moved to 2TB RAID5 members, that would reduce redundancy
        but replacing just two would gain me 2TB capacity. Most of the
        above still applies.
     3. If I kept to 1TB RAID6 (two on the 2TB drives), I would reduce
        the redundancy to just one drive if it was the 2TB drive that
        failed, but each new drive would gain me 1TB capacity and I only
        need to replace one-by-one. This sounds like the cheapest, but
        worst possible approach.

So, am I missing something? What do you think?
-- 
Michał (Saviq) Sawicz <michal@sawicz.net>

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