Disk Storage
- A virtual disk in a cloud caters to one virtual machine generally.
- Cloud offerings generally charge for hardware utilization.
- If the disk and virtual machine are created from same physical server
- disk will have temporary/ephemeral storage i.e. shutting down the vm will erase data
- If the disk and virtual machine are created from different physical servers
- disks will have persistent/non ephemeral storage i.e. shuttidng down the vm will not erase data
- AWS:
- Non ephemeral/persistent disks are called as EBS Volumes
- ephemeral/temporary disk are called as instance storages.
- Azure:
- Non ephemeral/persistent disks are called as Managed Disks
- ephemeral/temporary disksts are called as Temp/Local Disks.
- In both clouds the os disk (root volume) has to be persistent
- No cloud allows you to reduce disk size, they support only increasing the sizes
- VM Size has impacts on disk performance
- The compressed copy of the disk contents is called as snapshot (Backup of a disk)
- Snapshots are generated either incrementally or as part of full backups
AWS Disk Storage for single ec2 instance
-
AWS has two types of disks
- EBS Volumes:
- Default storage type for all root volume (disk with OS in it)
- This is supported in all ec2 instance types.
- Size is flexible
- Max number of EBS Volumes have nothing to do with instance types
- Instance Storage:
- This is supported only by few instance types
- Sizes are fixed
- Max number of instance stores are defined in instance type.
- EBS Volumes:
-
Disk Hardware types supported by AWS
- ssd
- hdd
- magnetic
Azure Disk Storage for single VM
- Azure has two types of disk
- Persistent
- OS Disk: Persistent and is supposed to be boot disk
- Data Disk: Additional persistent disks, Number of Data disks also depends on VM Size.
- Temporary
- Local Disk: Is more common is Azure
- This is temporary disk
- Size of Local Disk is fixed and is dependent on VM Size
- Local Disk: Is more common is Azure
- Persistent
- Disk Hardware types supported by Azure
- ssd
- hdd
