What is Primary Storage?
A primary storage is one or more servers that store volume files of VM instances. These files include root volume snapshots, data volume snapshots, image caches, root volumes, and data volumes.
The Cloud supports the following types of primary storage:
- Local Storage: This type of primary storage uses the hard disks to store disk files.
- Network Shared Storage: This type of primary storage supports NFS, Shared
Mount Point (SMP), Ceph, SharedBlock, AliyunNAS, and AliyunEBS.
- NFS primary storages use the network file system (NFS) to store files.
- SMP primary storages support network shared storages provided by commonly used distributed file systems, such as MooseFS, GlusterFS, OCFS2, and GFS2.
- Ceph primary storages use distributed block storages to store files.
- SharedBlock primary storages use shared block storages to store files.
- AliyunNAS primary storages use distributed files to store files.
- AliyunEBS primary storages use distributed block storages to store files.
The following table lists the relationship between primary storages and a cluster.
| Primary Storage | Cluster |
|---|---|
| LocalStorage | A cluster can have one or more LocalStorage primary storages attached. |
| NFS | A cluster can have one or more NFS primary storages attached. |
| SharedBlock | A cluster can have one or more SharedBlock primary storages attached. |
| SMP | A cluster can have one SMP primary storage attached. |
| Ceph | A cluster can have only one Ceph primary storage attached. |
| AliyunNAS | A cluster can have only one AliyunNAS primary storage attached. |
| AliyunEBS | A cluster can have only one AliyunEBS primary storage attached. |
| LocalStorage + NFS | A cluster can have one LocalStorage and one NFS primary storage attached. |
| LocalStorage + SMP | A cluster can have one LocalStorage and one SMP primary storage attached. |
| LocalStorage + Shared Block | A cluster can have one LocalStorage and one SharedBlock primary storage attached. |
| Ceph + SharedBlock |
|