Region/zone

[Update: November 28, 2018]

The following is an explanation of concepts for regions and zones which are used to indicate the location where resources exist in SAKURA Cloud.

Overview

In SAKURA Cloud, resources such as disks and servers are provided in a virtual format. However, the host servers and storage systems which actually house those resources are located in data centers throughout Japan. These locations affect a variety of elements including the mutual usability of resources existing in different areas, the scope and extent of impact on other locations when a problem occurs at a certain location, and network delay due to physical distance with the connection source client.

Therefore, in addition to design configuration to heighten resistance to malfunction and ascertaining the status at the time of malfunction, it is necessary to be aware of the physical location of each resource and to understand the features of those locations in daily operation. SAKURA Cloud uses the two concepts of regions and zones to indicate the physical location of resources.

Also, connection of servers and disks, copying from archives to disks, and other functions which use a virtual bus other than the L3 network can only be performed in the same zone. This restriction will also be explained.

Concept of physical location in SAKURA Cloud

SAKURA Cloud mainly uses the following two terms to indicate physical location.

  • Region: This unit is mainly assigned to individual cities such as Tokyo or Ishikari. Each region contains at least one zone. The individual zones are the actual targets of operation in SAKURA Cloud. Therefore, it is impossible to operate a resource directly in a region. However, the region is an important concept for ascertaining the physical location of zones which are subordinate to a particular region.
  • Zone: Zones are units which share facilities such as physical networks or power facilities. Zones located in the same region are physically isolated through measures such as installation in different rooms or different floors of the same building, or installation in different nearby buildings. However, the distance between zones is closer than the distance between regions. Consequently, it is possible that an overall malfunction at a certain building may affect multiple zones which are located in the same building.

The main differences between regions and zones are as follows.

  Region Zone
Minimum unit for locations Cities, prefectures, etc. Floor inside of a data center building
Data center Varies according to region May vary according to the zone or may be the same
Power facilities Not shared
*There is the possibility that the substation, etc., of the electricity company may be a single point of failure.
If other zones exist in the same building, power facilities in that building are a single point of failure.
Network facilities Connects with other regions via a backbone line using multiplexed routes Houses multiple zones in the same logical network on a higher level than the cloud
*It is possible that multiple zones will be affected at the time of a malfunction spreading throughout all areas of the logical network.
Network delay between locations Delay occurs due to physical distance of several kilometers to several 1,000 kilometers. The amount of delay in the same logical network is less than the delay between regions.
Distributed arrangement/redundant configuration between locations from a DR viewpoint Enabled Not recommend for the case in the same region

Switching zones at the control panel

SAKURA Cloud uses the notation of “region name + zone name” to indicate physical location (example: region"Ishikari" + zone "No. 1"). The zone switch menu at the top-left of the control panel uses this nomenclature to indicate the zone in which operations are being performed. (Sandbox is a test zone. You cannot create resources which actually operate. For details, please refer to Sandbox.)

Note

In actuality, even in the same zone, malfunction points and malfunction scope are distributed and localized via IP address bands, host servers, etc. However, zone is the minimum unit that can be intentionally specified by the customer for the arrangement location.

Operations only possible for resources in the same zone

The following operations can only be performed for resources which exist in the same zone. These operations cannot be performed for resources which overlap mutual zones, regardless of whether or not the resources belong to the same region.

  • Connect server and disk
  • Connection destination for NIC inserted into server
  • Connect switch
  • Copy archive and disk, or copy multiple archives
  • Archive created via auto backup
  • Mount ISO image
  • Load balancing using Load balancer appliance (*restriction via switch connection requirement)
  • Database connection to Database appliance (*restriction via switch connection requirement)
  • NFS connection to NFS appliance (*restriction via switch connection requirement)
  • Connection from lower-order network to VPC routrer (*restriction via switch connection requirement)
  • Server startup to Private host
  • Application of Packet filter
  • Target disk for Auto backup

Functions not dependent on region or zone

The following functions are not dependent on a region or zone. Resources are displayed and functions can be used regardless of which zone is selected. These types of resources are called “global resources.”

Convenient functions for use across zones

For the following services, it is possible to connect resources across zones. Using these functions enables configuration with redundancy and failure resistance while also heightening mutual usability.

  • Bridge connection: Enables L2 connection for switches between zones.
  • Hybrid connection: Enables L2 connection which includes other services provided by SAKURA internet, in addition to connection of zones in SAKURA Cloud.
  • Archive transfer function between zones: Enables replication of an archive to a different zone.