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Showing posts with label oracle performance tuning. Show all posts
Showing posts with label oracle performance tuning. Show all posts

Thursday 1 November 2012

What is SSD? How to get Good Performance from SSD?



Memory based disks or Solid state disks (SSD) are based on the concept of RAM disks. However, they are relatively more stable. An SSD is very similar to a standard disk drive and, for most practical purposes, behaves like one. To the host system, an SSD is a disk drive. But an SSD does not store data on magnetic disk media. Instead, it stores data on high density arrays of high speed DRAM memory chips. This eliminates the inherent mechanical delays that come with the need to spin a hard disk and position the read/write heads to execute an I/O request. By eliminating such latencies, SSDs achieve access times much faster than conventional disk drives. 

With most vendors, SSD performance is fast and reliable. An SSD has an integral battery-powered hard-disk drive and associated software continuously backing up its contents. At any moment, typically 81 percent of the data on the SSD is backed up to the hard disk. During power failures, batteries maintain power long enough to back up the rest of the data. In some implementations, backing up the contents onto disk is handled at the hardware level, enhancing performance and reliability further.

For database applications, SSDs provide a viable option for enhancing performance by eliminating variable seek times without compromising availability. Most vendors implement custom versions of the SSD concept. An instance, Sun Microsystems has PrestoServe, a high speed static memory-based storage medium that is backed up by lithium powered batteries. In typical Oracle implementations, small but heavy accessed files, such as online redo logs, Undo data files, can be placed on SSDs.

Most implementations of SSDs incorporate highly resilient fault monitoring during regular operations, which includes continuous header checking and data-retention system monitoring. However, have a chat with your vendor’s technical personnel and ensure that such checks are indeed continuous in your case. Also, have an arrangement with your vendor so that their technical personnel can visit your site and perform data-integrity checks at regular intervals, at least every three or four months. If possible, purchase tools from the vendor to conduct such tests in house, more often if necessary. For more assistance about performance tuning, kindly check our remote dba support services or directly contact us.

Tuesday 13 March 2012

How to Get Success in Oracle Performance Tuning?

This topic has been discussing so many times in different blog and different books. Every Oracle DBA is interesting to get success in Oracle performance tuning. I have published so many articles on same topic. Still I am asked same query by so many Oracle DBAs. Those Oracle DBAs are very keen to get answer to solve this mystery.

Oracle performance tuning doesn’t like mystery. Performance slowness would start in your database server and slowly it would be impacting all active sessions. Performance bottleneck doesn’t occur immediately and reflect drastically. But it started from very beginning and increasing rapidly sometimes. If you are well experienced Oracle DBA then you can judge for future impacts of some incidents. These symptoms and characteristics can be judged using constant monitoring of databases. If you are constantly monitoring your databases, then you can able to mark some incidents like buffer cache hit ratio suddenly dropped, temp segment usage suddenly improving, physical read is increasing, etc.

If you are keen in system administration then you would get these all characteristics of performance bottleneck very quickly and easily. Because in Linux and Unix environment so many utilities available to monitor Oracle server accurately about usage and load. As per my own opinion, I always use system administration tools for server monitoring like "top" command or "vmstat" command. Those are best monitoring tools.

Oracle installs on operating system. We need to concentrate on server performance and system load. If server has too much load then obviously Oracle database performance would affect. There is no question about it. So many performance issues are starting from Oracle server consumption only. It is just like health of people. If your stomach is not healthy then you would get so many health problems at any part of body.

I got one very good article on performance tuning of Oracle server from a resource. Oracle Performance Tuning Troubleshooting is art and techniques. To get expertise in tuning, you need to get various kind of knowledge like system administration, network administration, hardware, and applications. Without that knowledge, it is very difficult to understand main reason behind server slowness. In another word we can say it "without knowledge of application, system, network, hardware, Oracle server tuning becomes mystery for you".