https://dmsimard.com/tags/tutorial/ Recent content in tutorial on System Administration, Hosting, Cloud and technologies in between Hugo -- gohugo.io en-us Fri, 27 Mar 2015 00:00:00 +0000 https://dmsimard.com/2015/03/27/ceph-erasure-coding-overhead-in-a-nutshell/ Fri, 27 Mar 2015 00:00:00 +0000 https://dmsimard.com/2015/03/27/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 : 128 / 2 = 128TB Size 3 : 128 / 3 = 85.33TB Replicated pools are expensive in terms of overhead: Size 2 provides the same resilience and overhead as RAID-1.