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New storage infrastructure

As you will be seeing, the features are very interesting and we will be integrating them over time in your management interface as well as in the new API.

Improvements

Besides the disks, still using RAID for redundancy and a write cache resistant to a power failure, the storage servers are now organized in clusters: in case of controller failure, a standby controller is ready to take over the management of disks.

The storage capacity has been improved as well as disk I/O. Moreover, you will be soon able to create larger disks.

Creating, copying and resizing disks will be faster and more automated.

Snapshot

This mechanism enables you to create a snapshot of your disk that is either in use or detached. The snapshot can be used to achieve a consistent backup of your disk. Within a few weeks, a snapshot on demand will be available. We are also working on periodic management of snapshots. For example the ability to create a snapshot every day and only the last seven.

Copying disk

Thanks to the snapshots, it will be possible to create a fast and live copy of your disk, even with activity on it. This feature will facilitate fast deployment (clone) of servers.

Rollback

From a snapshot you will be able to create a disk, getting back your lost data or apply a rollback operation on your disk.

Automatic backup drive

A backup system, disk to disk, will be available in the future; we are still working on the specifications. For most of you, the snapshot mechanism will probably fulfill your needs.

Disks and Partitioning

Gandi disks are logical drives, meaning that we provide an access to disk already optimized, secured; it is easy to create new one, resize or delete them.

The partitions, or RAID algorithms are for your virtual machine, at best an unnecessary overhead, and at worst a reorganization of disk accesses that can result in performance degradation (see below). In addition, you can deprive yourself of convenient features: a snapshot made on a disk that is part of a RAID has no interest, resizing a partitioned drive (our old system) is complex even dangerous if not made carefuly.

Like with SSD and new hard disks, blocks are not 512 bytes long anymore but 4KB. If you are using partitions, access to your data may not be aligned, and performance divided by three.

Partitions are helpful for physical disks. This complicates the management of your disks for nothing: consolidate your data on a single disk or create multiple data disks is the right solution.

The disks created by Gandi will no longer use partitions. Currently only the system disks have a default partition (system and swap): it will disappear. The system disk will be managed like any other disk, which will facilitate management. To keep the same level of service, we will provide a temporary disk for swap. To remain consistent with the current configurations, we will emulate virtual partitions to present the system disk and swap: the system will be seen as xvda1, the swap as xvda2, like on the current system but it will be two different disks.



Note that the new storage infrastructure is available form the beginning in our Baltimore data center; features will be along the time.