Eliminate Hot Backup with EMC consistency technology

Bart Sjerps Oracle 3 Comments

For many years, EMC customers have been using storage replication technology to create copies of entire databases. Using storage cloning has many advantages over other mechanisms (file copy, tape restore, and the like). Most significant is that EMC storage can create near-instant copies of large applications without significant performance overhead. The reason is that the storage system is using its huge internal bandwidth and a couple of smart tricks to create the copy, therefore bypassing the host I/O layer.

Cloning
Cloning

In other words, a server running a database does not have to move a single bit of data for creating a copy of a multi-terabyte database.

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Through the wormhole with Stretched Clusters

Bart Sjerps Innovation, Oracle, VPLEX 5 Comments

Last year, EMC announced a new virtualization product called VPLEX. VPLEX allows logical storage volumes to be accessible from multiple locations. It boldly goes beyond existing storage virtualisation solutions (including those from EMC) in that it is not just a storage virtualisation cluster – but merely a storage federation platform, allowing one virtualized storage volume to be dynamically accessible from multiple locations, as if they were connected through a wormhole, and being built from one or more physical storage volumes.

Wormhole in space
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Stretched Clusters – Alien storage

Bart Sjerps Oracle, VPLEX No Comments

In my previous posts I described how Oracle ASM can be used to build stretched clusters. I also pointed to some limitations of that scenario. But I am by far not the first one in doing so – and some of EMC’s competitors attempted to build products, features and solutions to overcome some of the limitations in host mirroring.

A while ago, some guys I met from an EMC partner, confronted me with the question why EMC, the market leader in external storage and premium Oracle technology partner, had not offered a solution for these limitations. They pointed to a number of products from competitors that – allegedly – solved the problem already. Also they pointed to the architectural simplicity of these solutions.

Alien Storage

At that time I had no good answer (which does not happen to me very often). I was not aware of how these products worked and I asked some questions on that. In that period I was also confronted by our enterprise customers who started demanding an EMC solution for stretched clustering – so I started digging. Could it be that EMC was over-passed by some of these alien storage start-up companies in continuous available storage solutions? It seemed to be the case.
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Stretched clustering basics

Bart Sjerps Oracle, VPLEX No Comments

Before showing my preferred solution for Oracle stretched high availability clusters, first some clustering basics.

Active/passive versus Active/Active clusters

NASA cluster
NASA cluster

Most clustering software is based on active/passive scenarios. You have a system (say, a database) that is running on a set of resources (i.e. a server, to keep it simple) and you have another system (a standby system) that is ready to run the system (failover) but is not actually running it at the same time.

An Active/Active system in general means both systems are active at the same time. There is some confusion as this can mean that the standby system is used for other processing (say, A is production and B is standby but currently running acceptance or testing environments).

By my definition, active/active clustering describes a cluster where all cluster nodes (systems) are processing against the same data set at the same time. There aren’t many products that can do this, especially in the database world. One of the few exceptions is Oracle RAC.

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