Oracle OpenWorld 2011 Technical Sessions: Part 1

This begins a series of blog posts on the subject of technical sessions that EMC presented at OOW2011. To begin with, we will examine the session that I co-presented with Kevin Jernigan entitled Clone Oracle Databases Online in Seconds with Oracle Clonedb and DirectNFS. The presentation for this session can be found here.

It may sound strange given EMC's reputation and history, but EMC has a strong partnership with Oracle in the area of NAS. We began working with Oracle on the Direct NFS client ("dNFS") way back in 2007, when dNFS was introduced as a major new feature in Oracle Database 11g Release 1. At that time, EMC, was a co-presenter (together with Oracle) at Oracle OpenWorld 2007 on this subject.

The goals of dNFS were simple, and well defined:

• Improve performance (in terms of latency and throughput) of NFS-mounted Oracle database I/O
• Reduce CPU cost of NFS-mounted Oracle database I/O
• Improve network port scalability and failover of NFS-mounted Oracle database I/O
• Simplify administration of NFS in terms of both network port scaling and mount point parameters
• Make administration of NFS uniform across all platforms

dNFS succeeds widely at all of these. dNFS dramatically improves latency of network I/O from Oracle by eliminating most context switches and making the code path to the disk much shorter. dNFS also provides better port scaling than kernel NFS, with much simpler administration. No fussy ether channel network switch configuration is required. All of the port scaling and port failover is provided within the Oracle environment.

 

dNFS also made administration completely uniform across all platforms. Amusingly, Windows is included! NFS now works on Windows, at least with an Oracle database.

In September 2010, Oracle announced that dNFS would be improved in Oracle Database 11g Release 2. One major improvement is the addition of dNFS clonedb, a thinly-provisioned, rapid database replication feature. This feature also works very well with storage-based replication.

 

The basis for dNFS clonedb is a database copy. This copy can be a backup, a storage-based snapshot or clone, or an operating system copy. (Of course, EMC likes to leverage our storage-based snaps and clones.)

 

Once a copy exists, it can be used to create a clonedb instance. The steps to do this are contained in My Oracle Support article 1210656.1 . Effectively, this creates a read / write virtual database which takes up minimal space, is created almost instantly, and contains only the space required to store any changes to the database. Given that storage-based snapshots are also space and time efficient (that is, they take up very little space, and can be created very quickly) there is a great deal of synergy between these technologies.

 

EMC did some performance testing with dNFS clonedb. The network diagram for the testbed is here:

First, we established a baseline in terms of performance. We ran an OLTP workload against the production database with no additional operations. This produced the following:

Notice the perfectly clean scaling of this performance chart. We then tested the performance of creating a snapshot to serve as the source for the clonedb database. This produced:

Note the slight response time hit when the snapshot was taken. However, transactional throughput was not affected. Basically, this is at most a minimal performance hit. Finally we tested performance while creating clonedb database instances from the storage snapshot. This produced:

Note that there was no performance hit during clonedb creation at all. One additional test was performed. We measured the storage space occupied by the clonedb when it was created. A 10 TB database was used as the source. The total space occupied by the clonedb was only 7 MB.

See the link above for the full presentation of this technical session. Further blog posts in this series will contain summaries of other EMC technical sessions at OOW 2011.