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Our requirements from the storage are pretty much the same any other cloud provider has:-
- Full disk encryption. In more traditional cloud providers this is done to guard users from each other and from cloud provider employees. Guaranteeing that data will never leak. In our conditions we also don’t like the idea of the device being stolen, and unencrypted data can be accessed
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- Thin provisioning. Efficient usage of the storage - the blocks which are not used by a user should not be occupied
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- Snapshotting. Snapshot a state of guest and easily roll back or forward between the snapshots
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- Compression also adds up to the efficiency of storage usage. And as well might increase read speeds on slower volumes (e.g. emmc)
Problem with current architecture
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Here another advantage of the Intermediate step appears. If a production-ready zfs-based solution comes before the next wave of customers, we will endup with fewer nodes based on the legacy storage format. And transitioning from SCSI-vhost to NVMe-vhost is significantly easier than reformatting the whole system disk.
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- /dev/vda for virtio-scsi (current Eve implementation)
- /dev/sda for vhost-scsi-pci (implementation described in the chapter Intermediate step)
- /dev/nvme0n1 for nvme emulation
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We will get the first numbers already pretty soon, when the Intermediate step PoC is ready. This would be also interesting to see what is going to be the bottleneck of such architecture, and potentially adjust the development plan according to the discoveries.
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