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I'm considering using LVM striping over several EBS volumes. So let's imagine the following case: Volume group DATA is created with 3 physical disks sdf1, sdg1 and sdh1. I create a logical volume "store" inside DATA and enable striping on this, with 3 stripes and a stripesize at 128KB so I split my blocks across the 3 physical volumes.

Now, I want to add a 4th physical volume to grow the size of the volume group and logical volume. I add my physical volume to DATA, increase the size of "store" and change the number of stripe from 3 to 4.

What happens to my "store" volume ? Do the previously existing blocks get re-organized ? Otherwise, if my 3 previous physical volumes were full, only the 4th one will be used to store the new blocks, and there would be no striping.

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Do the previously existing blocks get re-organized?

Nope.

What you would get is a LV that is a concatenation of two stripe sets, one 3 disks and one 4 disks.

However, if you going to extend and LV with stripes then the maximum size of the extension is N * the number of free extents on the PV with the fewest free extents where N is the number of stripes.

In your case the three current disks are full. Thus you cannot use striping at all.

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  • Another issue is IOPS. The IOPS GP2 provides is barely enough, if you stripe 3 of them you'll have one 1/3 of IOPS remaining. You could switch to IO1 provisioned IOPS disks, but those are barely better than the GP2 and cost a multiple. At this point (2019) Amazon does not have any storage option that is equaly in performance as a low end computer. It is highly reliable but also very slow.
    – John
    Jan 22, 2019 at 1:34

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