Description:
- Every Compute Engine VM instance is attached to at least one disk as a boot disk and for persistent storage.
- A disk is partioned and managed by Google
1. Disks:
- Choose which Boot disk image for VM to start from
- Custom or public
- Some public images are premium, charged per second/minute
- can be from 4. Compute Engine Machine image
- So it will come with a single root persistent disk
- Advance
- Deletion rule:
- Normally the boot disk defaults to being deleted automatically when the instance is deleted.
- You can override it so u can ==recreate system Compute Engine Machine image== from boot disk of a terminated vm
- Persistent disk vs Local SSD vs RAM disk:
- Persistent disk
- Attached to the VM through the network interface, not physically
- Survices if the Vm terminates
- HDD vs SSD
- Can be resized while its running
- Can also attach a disk in read-only mode to multiple VMs.
- Shared so cheaper than replica
- Can be zonal or regional
- pd-standard: persistence disk HDD
- pd-ssd
- pd-balanced
- pd-extreme (zonal)
- Local SSD:
- Physically attached to the VM
- Ephemeral but much faster than persistence
- Lose data when Vm stop or terminate
- Cant be shared between VMs
- RAM disk:
- tmpfs
- fastest for high-memory vm
-
| Persistent HDD | Persistent SSD | Local SSD | Ram disk |
|---|
| Data redundancy | Yes | Yes | No | No |
| Encryption at rest | Yes | Yes | Yes | N/A |
| Snapshotting | Yes | Yes | No | No |
| Bootable | Yes | Yes | No | Not |
| Use case | bulk file | faster | very fast | fastest but have data loss |
- Location:
- Source:
- Location:
- A disk can be in 1 regional but many zone as failover replica
- can have many disk with different os
2. Snapshots
- Only available to persistent disk
- Are incremental, like git, unlike a machine image
- they can be used to:
- backup critical data into a durable storage solution to meet application, availability, and recovery requirements.
- Transfer data from 1 zone to another
- transfer data to another disk type
- stored in Google Cloud Storage