An Oracle blog about ZFS Storage

  • February 10, 2015

Thin Cloning of PDBs is a Snap with Oracle Storage

Guest Author

I thought I’d bring up another integration point between Oracle
ZFS Storage Appliance and Oracle Database 12c with Oracle Multitenant.  Specifically,
I want to discuss how we integrate our ZFS snapshot technology with Oracle
Multitenant to reduce database storage footprint and speed database
provisioning straight from the SQL Plus command line.

Oracle Multitenant option for Oracle Database 12c introduces
the concept of the pluggable database (PDB), which exist within a container
database (CDB).  This is the basic construct that is used to facilitate
database creation in multitenant environments from either “seed” PDBs
(essentially a template) or a “source” PDB (an existing, running, full
database).  In either case, a simple SQL Plus command “create pluggable
database…” is used to easily create the new PDB.  Under the covers, the way
this normally works is by duplicating the relevant files associated with the
source or seed PDB, copying them to a new location to support the new PDB.

But the Oracle ZFS Storage Appliance has thin cloning
capability based upon ZFS snapshots and ZFS clones.  This leverages the unique
copy-on-write architecture of the ZFS filesystem to enable administrators to
create a nearly infinite number of snaps / clones in a manner that occupies
almost no initial storage space, takes negligible amount of time to create, and
causes negligible performance impact to existing workloads.  Is it possible to
leverage this technology for deploying PDBs in a Multitenant environment?  Yes!

We offer ZFS snapshot integration straight from the SQL Plus
command line.  This integration allows a DBA to utilize the same “create
pluggable database…” to easily create a new PDB from an existing source or seed
PDB.  But, the twist is you no longer actually have to copy files.  By adding
the “snapshot copy” suffix to the same SQL Plus command, you invoke the ZFS
snapshot and cloning functionality behind the scenes, transparently and
automatically.  This inserts copy-on-write pointers to the existing PDB rather
than copying the actual files.  The upshot is that you provision the same new
PDB just as you would have using the original method, but the new PDB will
occupy almost no incremental storage space initially after clone creation. 
Also, creation of the new PDB happens in seconds because no data is actually
being copied from place to place.

How does this all work?  Check out href="http://www.oracle.com/technetwork/articles/servers-storage-admin/multitenant-on-sparc-solaris-2016889.html#7">this
article on using snapshot cloning in an example infrastructure with Oracle
Multitenant and SPARC servers.

So, with Oracle ZFS Storage Appliance and Oracle Multitenant,
creating new PDBs from existing PDBs is extremely simple, carries no initial
storage footprint, and very happens very fast.  Which means reduced disk costs
and also reduced management time related cost.  This is yet another example of
deep integration between Oracle products that are designed to work together.

See my related video at: href="https://www.youtube.com/watch?v=1E2KIbaBPRs">https://www.youtube.com/watch?v=1E2KIbaBPRs

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