Mirror View

MirrorView is a software application that maintains a copy image of a logical unit (LUN) at separate locations in order to provide for disaster recovery, that is, to let one image continue if a serious accident or natural disaster disables the other.

The production image (the one mirrored) is called the primary image; the copy image is called the secondary image. MirrorView supports up to two remote images, but since we operate on one image at a time, the examples in this document show a single image. Each image resides on a separate storage system. The primary image receives I/O from a host called the production host; the secondary image is maintained by a separate storage system that can be a stand-alone storage system or connected to its own computer system. The same management station, which can promote the secondary image if the primary image becomes inaccessible, manages both storage systems.

Configuration Guidelines

The following are configuration rules for MirrorView:

Each mirror can have one primary image and zero, one, or two secondary images. Any single storage system can have only one image of a mirror.

A storage system can have mirroring connections to a maximum of four other storage systems concurrently. You can configure a maximum of 50 (25 on CX400 and CX500) primary images to use the write intent log. In addition, a single storage system can host no more than 100 total images (50 on CX400 and CX500), counting MirrorView primary and secondary images, as well as Clone images and their source LUNs.

Prerequisites

We must have the MirrorView and Access Logix™ software installed and enabled on all CX-Series storage systems we want to participate in a mirror. We must have Navisphere Manager installed and enabled. All the systems participating in the mirror must be in the same domain.

MirrorView Features and Benefits

MirrorView mirroring has the following features:

Provision for disaster recovery with minimal overhead CLARiiON® environment Bidirectional mirroring Integration with EMC SnapView™ LUN copy software

Provision for Disaster Recovery with Minimal Overhead

Provision for disaster recovery is the major benefit of MirrorView mirroring. Destruction of the data at the primary site would cripple or ruin many organizations. After a disaster, MirrorView lets data processing operations resume with minimal overhead. MirrorView enables a quicker recovery by creating and maintaining a copy of the data on another storage system.

MirrorView is transparent to hosts and their applications. Host applications do not know that a LUN is mirrored and the effect on performance is minimal. MirrorView uses synchronous writes, which means that host writes are acknowledged only after all secondary storage systems commit the data.

MirrorView is not host-based; therefore it uses no host I/O or CPU resources. The additional processing for mirroring is performed on the storage system.

Bidirectional Mirroring

A single storage system may be primary (that is, hold the primary image) for some mirrors and secondary (that is, hold the secondary image) for others. This enables bidirectional mirroring.

Mirror View implementation

Here CX500 named top is treated as source and cx500 named bottom is treated as destination. Login to navisphere which gives access to both cx’s

Once you are able to see both cx500’s , expand the cx500 named top, bind a lun to it in the following manner

Once the lun is created , right click on the LUN and select mirror view --> Create remote mirror

Once a remote mirror is created it appears to be mirrored with out secondary image , for adding secondary image right click on it select mirror view and hit on secondary image lun

It creates a secondary image lun of same size on other cx500 , now once this is created right click on remote mirror , in this case demo mirror view and click add secondary image .Once secondary image is added it is queued for synchronization and then sync started

Sync started at 5:03 , and ended at 5:53 PM on FC to FC 100 GB initial sync .Once the initial sync is done from next time only blocks that get modified only gets replicated .And at a point of failure of primary image the secondary can be promoted immediately as a primary copy.