Friday, February 13, 2015

Snap Clone using EMC SAN and ASM

By Pete Sharman

Recently we announced the latest update to Enterprise Manager Cloud Control 12c Release 4.  One of the enhancements in that release is support for Snap Clone on Automatic Storage Management (ASM) and EMC Storage. Before we examine the details of this specific enhancement, let's look at a quick refresher on what Snap Clone provides for you.

What is Snap Clone?

Snap Clone is a storage agnostic and self service approach to creating rapid and space efficient clones of large databases (and by large, we’re talking terabytes or more). Now that’s probably more buzz words in one sentence than anyone’s brain can deal with without exploding, so let’s explain some of those terms more:
  • Storage agnostic – by that I mean Snap Clone supports all storage vendors, both NAS and SAN. It can leverage storage layer APIs or layer a ZFS filesystem on top to provide copy on write.
  • Self service – in the XaaS world – where X can be any of I, MW, P and DB :) – one of the key features is empowering the end user to do the work, rather than waiting on some techie to find time in their otherwise busy schedules. So it’s the end user who makes the adhoc clones here, not the storage admin
  • Rapid – People simply don’t have the time to wait weeks for provisioning to happen any more, so you have to support the functionality to clone databases in minutes rather than the days or weeks things used to take.
  • Space efficient – When you’re working with terabyte or larger databases, you simply may not have the storage to create full-sized clones, so you have to significantly reduce the storage footprint to start with.
Over the various EM releases,  more and more functionality has been added to Snap Clone:
  • EM12cR2 provided Snap Clone for NAS storage (NetApp and Sun ZFSSA).  It provided RMAN backup based clones, and included the Snap Clone Analyzer to show you the storage savings you could make using Snap Clone
  • EM12cR3 added in support for Snap Clone using the Solaris File System (ZFS) and admin flows for Snap Clone for PDB’s (pluggable databases)
  • EM12cR4 added a lot more:
    • Snap Clone using CloneDB – this is the biggie, as it means Snap Clone can now be used with ANY Oracle database release that supports CloneDB, regardless of what storage it’s on
    • Data Guard standby as a test master – allows offloading the impact of creating the test master from your Production environment
    • NetApp Ontap 8.x cluster mode support
    • Certification for engineered systems, with I/O over Infiniband
    • Support for NFSv4
  • And in the latest plugin update that's just been shipped, we added:
    • Integrated data lifecycle management
    • Snap Clone using EMC SAN and ASM
    • Admin flows for test master creation
    • Integration with masking, patching, upgrades etc.

Snap Clone using EMC SAN and ASM

Most NAS technologies offer storage efficient clones in the form of Snapshots. The snapshots make use of underlying volumes, knows as flexvols (Netapp) or shares (ZFS). Unfortunately, SAN storage does not provide native snapshotting capability unless a file is created on it by leveraging TCP/IP over iSCSI over Ethernet. However this defeats the purpose of having high speed fiber channel fabric, not to mention that it makes little sense to overlay SAN with a filesystem. Another complaint we heard from our customers is that cloning is a data intensive operation that could flood the corporate IT backbone if Ethernet is used. Consequently, lot of our customers want native support for SAN for cloning purposes, especially, the ones who run ASM on SAN. And they are quite a lot in number.

Using Snap Clone on ASM and EMC storage provides the ability to create ‘live’ thin clones of databases that are on ASM. A live clone is NOT snapshot based but rather a live copy of the database, residing on copy-on-write storage technology, that can be within the same cluster or indeed another one. Both single instance and RAC are supported – supported versions are or higher of the database, 11.2 and higher of the Grid Infrastructure code. This functionality works on both EMC VMAX (with Time Finder VPSnap) and VNX storage appliances.

Diagrammatically, the configuration looks like this:

Why Use Snap Clone with EMC SAN and ASM

There are a number of major challenges that Snap Clone can be used to address:
  1. Lack of automation - Manual tasks such as provisioning and cloning of new databases (for example, for test or development systems) is one area that many DBA’s complain is too time consuming. It can take days to weeks, often because of the need to coordinate the involvement of different groups, as shown in the image below:
  2. When an end user, be it a developer or a QA engineer, needs a database he or she typically has to go through an approval process like this, which then translates into a series of tasks for the DBA, the sysadmin and storage admin. The sysadmin has to provide the compute capacity while the storage admin has to provide the space on a filer. Finally, the DBA would install the bits, create the database (optionally on Real Application Clusters), and deliver that to the user. Clearly, this is a cumbersome and time-consuming process that needs to be improved on.

  3. Database unfriendly solutions – Obviously, when there is a need looking for a solution, different people take different approaches to solving that need. There are a variety of point solutions and storage solutions out there, but the vast bulk of them are not database aware. They tend to clone storage volumes rather than databases and have no visibility into the database stack, which of course makes it hard to triage performance issues as a DBA. They also lack the ability to track configuration, compliance and data security issues, as well as having limited or no lifecycle capabilities. As mentioned before, DBAs would like to leverage the native FDDI protocol of SAN for cloning.  This will make cloning fast and efficient without disrupting regular network traffic.
  4. Storage issues and archaic processes – Of course, one of the main issues is storage. Data volumes are ever increasing, particularly in these Big Data days, and the growth can often outpace your storage capacity. You can throw more disks at the problem, but it never seems to be enough, and you can end up with degraded performance if you take the route of sharing clones between users. There can also be different processes and different priorities between the storage team and the DBA team, and you may still have fixed refresh cycles, making it difficult to clone on an adhoc basis.
So the end result of all of this is that far too often, there are competing priorities at odds. Users want flexibility – simplified self service access, rapid cloning, and the ability to revert data changes. IT, on the other hand, want standardization and control, which allows a reduction in storage use, reduction in administrative overhead, visibility into the complete database stack and lineage tracking.  

Snap Clone on EMC storage helps you to address all these competing priorities, using hardware you may already own.  Indeed, EMC is well established as an Oracle database storage vendor over many years, and that integration has become tighter and tighter over the past few years.  In addition to that, the actual setup and configuration can be simpler than is the case when using other hardware, as you do not need to create Database Profiles in this configuration.  Service Templates are created directly on either a single instance or RAC database that resides on ASM.  Because you're using this combination of ASM and EMC SAN storage, the database is already Snap Clone enabled as it resides on copy-on-write storage technology.

In my next post, I'll discuss more details of what else is new in the Snap Clone product in this latest release, so stay tuned for more details on that soon!

For More Information

You can see more details on how you actually set Snap Clone up on EMC storage by viewing the following screenwatches:
For more details on using Enterprise Manager Cloud Control 12c to provide Database as a Service functionality, visit the OTN page located here.

Blog Entry written by Pete Sharman.

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