Sql-server – Sql Server – Best Practices for Growing Database Files

best practicessql serversql-server-2008sql-server-2008-r2transaction-log

I have been monitoring file growth via the data collector in sql server 2008 r2 for two weeks. The database is growing consistently at around 35(MB)/Day. The DB has not yet hit the initial size of 2 GB.

The DB files auto growth is set to 5MB and I would like to try a different approach, so I am looking for suggestions and or comments.

There is a tuning task that runs every-week on Sunday night at 1:30 AM. The task will:

  • Check Database Integrity
  • Shrink the Log File – (This is ok because logging mode is Simple)
  • Shrink Database
  • Reorganize Index
  • Rebuild Index
  • Update Statistics
  • Clean Up History

I would like to add two more steps to the weekly tuning plan:

  1. Grow the database file by 500 MB if the used space reaches a certain threshold or total size.
  2. Grow the log file by 250 MB (after the shrink) if the used space reaches a certain threshold of total size.

By placing the growth burden in offline hours, I hope to gain performance by reducing the number of auto-growth events during heavy loads.

I have two questions relating to auto growing files.

  • The best place to put the file grow steps would be prior to the current steps or after?
  • If I use the ALTER DATABASE|MODIFY FILE to grow the file then how can I determine if SpaceUsedInFile >= (TotalFileSpace-@AllowanceThreshold)?

Best Answer

You should be aiming to auto-grow as little as possible. Seven times a day is excruciating, even with instant file initialization.

Don't do a Shrink Database. Ever. Shrinkfile, maybe, but only after an extraordinary event. Shrinking it just to grow again is an exercise in futility and should actually be called auto-fragment.

If recovery model is simple, there is no way on earth you should need to grow your log file by 250 GB. The used space in the file will clean itself out automatically over time, unless you started a transaction a month ago and have no intentions of ever committing it or rolling it back.

So my advice would be:

Auto-grow the data file manually during a quiet period to a size that will accommodate several months of growth. What are you saving it for in the meantime?

Set the auto-growth increment for the data file to something relatively small (so that it doesn't interrupt users when it does happen), and alert on this event (you can catch it in the default trace, for example, or through extended events). This can tell you that you are hitting the high point you estimated and it is time to grow manually again. At this point you will want to keep this manual in case you want to add a new file / filegroup on a different drive to accommodate the space, since eventually you will fill the current drive.

Auto-grow the log file to, say, twice the largest it's ever been. It shouldn't auto-grow further unless there is some abnormal transaction holding things up. You should monitor for this event as well, so that you know about them.

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