The FlashSystem™ V840 AC1 control enclosure combines software and hardware into a comprehensive, modular appliance that uses symmetric virtualization.
Symmetric virtualization is achieved by creating a pool of managed disks (MDisks) from the attached storage systems. Those storage systems are then mapped to a set of volumes for use by attached host systems. System administrators can view and access a common pool of storage on the storage area network (SAN). This functionality helps administrators to use storage resources more efficiently and provides a common base for advanced functions.
A system of FlashSystem V840 nodes presents volumes to the hosts. Most of the advanced functions that FlashSystem V840 provides are defined on volumes. These volumes are created from managed disks (MDisks) that are presented by the RAID storage systems. All data transfer occurs through the FlashSystem V840 node, which is described as symmetric virtualization.
The nodes in a system are arranged into pairs that are known as I/O groups. A single pair is responsible for serving I/O on a volume. Because a volume is served by two nodes, no loss of availability occurs if one node fails or is taken offline.
The FlashSystem V840 nodes in a clustered system operate as a single system and present a single point of control for system management and service. System management and error reporting are provided through an Ethernet interface to one of the nodes in the system, which is called the configuration node. The configuration node runs a web server and provides a command-line interface (CLI). The configuration node is a role that any node can take. If the current configuration node fails, a new configuration node is selected from the remaining nodes. Each node also provides a command-line interface and web interface for initiating hardware service actions.
I/O operations between hosts and FlashSystem V840 nodes and between FlashSystem V840 nodes and RAID storage systems use the SCSI standard. The FlashSystem V840 nodes communicate with each other through private SCSI commands.
Table 1 shows the fabric type that can be used for communicating between hosts, control enclosures, and storage enclosures. These fabric types can be used at the same time.
| Communications type | Host to AC1 control enclosure | AC1 control enclosure to AE1 storage enclosures | AC1 control enclosure to AC1 control enclosure |
|---|---|---|---|
| Fibre Channel SAN | Yes | Yes | Yes |
| iSCSI (10 Gbps Ethernet) | Yes | No | No |
| Fibre Channel Over Ethernet SAN (10 Gbps Ethernet) | Yes | No | No |
Each FlashSystem V840 node is an individual server in a FlashSystem V840 clustered system on which the FlashSystem V840 software runs.
I/O groups take the storage that is presented to the SAN by the storage systems as MDisks and translates the storage into logical disks (volumes) that are used by applications on the hosts. A node is in only one I/O group and provides access to the volumes in that I/O group.
The AC1 control enclosure has the following features: