Converting between General Purpose (SSD) and Magnetic Storage


We want to convert our MySQL storage from Magnetic Storage (currently 65gb) to General Purpose (SSD) gp2, which we are running a single instance (no Multi-AZ). However when I select the storage type we are prompted with the following warnings

If you convert between General Purpose (SSD) and Magnetic Storage, it can cause these issues:

  • Deplete the initial General Purpose (SSD) I/O credits, leading to longer conversion times.
  • Impact instance availability for up to 2 minutes for Multi-AZ and for several minutes for Single-AZ.
  • Negatively affect instance performance until the operation completes.

I was under the impression that if we convert from Magnetic to General Purpose (SSD) we shouldn't have any degrade in performance, but these warnings suggest otherwise.

Current storage

Current storage

Warning if we change to gp2

Warning if we change to gp2

Information if we change to gp3

Information if we change to gp3

1 Answer

Well, the warning indicates that you might be trying to convert from GP2 to HDD. Are you sure you are really doing the oposite ?

IF you are really changing from HDD to GP2:

Any performance degradations you might see in a warning are only while your volume is being replaced, which can take several minutes. After the operation is completed you will get the benefits of the GP2 volume.

General guidelines to perform this operation:

  • Before anything take a manual snapshot in case anything goes wrong and you need to recover;
  • Apply the changes during periods of low database utilization, to reduce impact.

Given your disk size of 65GB, you may consider changing to GP3 volume type, since they give better baseline IOPs performance and 20% reduced cost per GB. Check here for gp2 and gp3 comparison.

answered 10 months ago
  • I've commented on our question to include the screenshots of the warning. We are really changing from magnetic to gp2.

  • The warning is because GP2 has it's IOPs tied to it's size, you get only 3 IOPs per GB, so you would have only 195 IOPs to begin, which could not be enough and would make it take a lot longer. GP3 volumes are the way to go for small size volumes. Just don't forget to snapshot first and to do it when database is not busy.

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