Migrating Glance images to a different backend

The use case

This isn’t exactly far-fetched but nothing seems to do it out of the box: migrate Glance images from a backend to the other.

We’re in the process of moving our Glance default store to Swift, it simply scales infinitely better than the file backend. Now ...

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Ceph erasure coding overhead in a nutshell

Calculating the storage overhead of a replicated pool in Ceph is easy. You divide the amount of space you have by the “size” (amount of replicas) parameter of your storage pool.

Let’s work with some rough numbers: 64 OSDs of 4TB each.

Raw size: 64 * 4  = 256TB
Size 2 ...
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