Very basic and generic discussion from the performance point of view. Customers still have to do their due diligence in understanding redo logs, and how they work in Oracle database, before finalizing redo log configuration for their deployments.

• size them properly
  • log writer writes to a single redo log file until either it is full or a manual log switch is requested
        Oracle supports multiplexed redo logs for availability, but this behavior of writing to a file until it is full or a log switch happens, still hold
  • if the transactions generate a lot of redo before a database commit, consider large sizes in tens of gigabytes for redo logs
  • if not sized properly, it leads to unnecessary log switches, which in turn increase checkpoint activity resulting in unnecessary slow down of the database operations
        two redo logs each with at least 5G in size might be a good start. observe the log switches, checkpoints and increase (or decrease, though there is no performance benefit) the file size accordingly
  
  
• do not mix redo logs with the rest of the database or anything else
  • in a normal functioning database, most of the time, log writer simply writes redo entries sequentially to redo logs
  • any slow down in writing the redo data to logs hurt the performance of the database
  • best not to share the disks/volumes on which redo logs are hosted, with anything else
        set of disks, volumes exclusive to redo logs, that is
  
  
• ensure that the underlying disks or I/O medium used to store the redo logs are fast, optimally configured and can sustain the amount of I/O bandwidth needed to write the redo entries to the redo logs
      if those requirements are not met, it could lead to 'log file sync' waits, which will slow down the database transactions
  
  
• redo logs on non-volatile flash storage may have performance benefits over the traditional hard disk drives
  • check this blog post out, Redo logs on F40 PCIe Cards, for related discussion (keywords: 4K block size for redo logs, block alignment)

Labels: Oracle Database RDBMS Redo Flash+Storage

Posted by: Giri Mandalika.    # 1:51 PM 0 comments.     Tweet

Music and Movies - the two powerful forms of entertainment, are very subjective. In general, there is no good or bad music, and there are no good or bad movies. Their success depend on a combination of various factors such as the mood we are in, our biases, memories, brand (eg., Pixar in movies; The Beatles in music, although I never came across any palatable original work from this boy-band group), derivation from other successful work -- remixes (Fatboy Slim), mashups (DJs), mockery (spoof movies, comedy skits), influence/herd mentality (Bieber, Miley on Billboard top singles), celebrity endorsements, timing of their release (cliched superhero summer tent-poles), their competition (someone will emerge as a winner even when the actual content and its presentation is equally weak), marketing push (Kelly Clarkson, The Avengers movie), viral status (Gangnam Style), cult following (Office Space), audience desperation, events that evoke feelings such as happiness, smugness, sympathy (Heath Ledger's death helping Nolan's Batman series) and pity (MJ's "This is it"), luck, the artists, crew and of course, the actual content. In short, if something was "well liked", it does not necessarily mean that it was really "well liked" -- multiple factors surrounding that piece of work must have properly aligned and helped in one way or the other, to make it more successful.

Now that the obvious disclaimer is out of the way, I think I can openly list out some of the stuff that I think is worth listening to. If you don't like or really hate something that you see here, too bad I guess - just deal with it. :-)

To kick start this series, I chose a handful of oldies from 50s, 60s and 70s. (yes, I intend to publish a few more playlists down the line, unfortunately). Here it goes in no particular order. I really like those shorter 2+ minute durations. Audio-Visual material courtesy: YouTube.

Before concluding: I do not know much about composing music, or playing musical instruments of any kind. Still I attempted composing a few instrumental tracks with the help of software. It's been a fun exercise so far. Listen to those amateur tracks @ icompositions | giri04 webpage.

Labels: music

Posted by: Giri Mandalika.    # 3:14 AM 1 comments.     Tweet