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Frank Barcenas
Asked: 2020-08-03 15:50:38 +0800 CST

3ware: Is it possible to add a new drive to an existing raid5 set?

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I would like to know if it's possible to add a new drive to a raid5 set with the purpose to expand the storage available in the set. 9550 controller

For example to go from: 4x1TB drives to 5x1TB drives and do a resizefs on my linux partion and have it encorporate the empty space to the partition.

raid 3ware

1 Answers

  1. Best Answer

    First of all, you should not use RAID5 today. Once a single drive fails in your setup and you replace it, it is very likely that a second drive fails during rebuild phase, and all your data is lost.

    Your best option is to upgrade to at least RAID6.

    I'm also pretty sure that you cannot add new drives to any RAID5 setup. This is because the way RAID5 works. For a set of data called stripe, it writes the actual data to drives 1 - N-1 and writes parity information to drive N. For the next stripe of data, data is written to drives 2 - N, and parity information to drive 1.

    This rotation of stripes will happen for every stripe.

    Now, if you add a new drive to the set, all the stripes have to be rewritten since there are now N+1 drives.

    This means that you need to rebuild the storage from scratch.

    Therefore it is now a good time to upgrade your storage system to a reliable one.

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