Microsoft SQL Server uses transaction logs in order to increase I/O performance. Transactions are written to the log file faster than they can be written to the database, and are then copied into the database in the background. Embotics vCommander™ supports two recovery models: simple recovery and full recovery.

Simple Recovery


Simple recovery logs only uncommitted transactions, which are those that have not yet been written to the database. Once a transaction has been written to the database, or committed, the log entry is removed. This does not reduce the disk space consumed by the log file, however, as SQL Server will reclaim and use the space within the log file but will not release space back to Windows. Use the SQL Server to see the available space within a log file.


The size of the log file will grow to its maximum size based on the amount of activity in Embotics vCommander. More service requests and virtual machines under management will mean more space is required. The space used by the log will always increase in size and will never shrink on its own. Running a backup will not shrink the log file, so when using Simple Recovery a shrink should be performed should the log file increase in size significantly month to month.


Using simple recovery mode you will usually see much less disk space taken up by the log files.


Full Recovery


Full Recovery logs committed and uncommitted transactions. Once a transaction has been written to the database, or committed, the log entry is not removed. This causes the log file to grow in size until the next successful backup occurs. When the backup completes, the space occupied by committed transactions is reclaimed within the log file. Size will appear unchanged unless a shrink operation is performed.


Running a backup will not shrink the database, nor will a manual shrink significantly reduce the overall size of the log. The only reduction in the size of the log file will come from successful backups combined with a shrink operation. This means that in order to contain the log file growth, you must schedule more frequent backups, at least on a daily basis.


A full backup is used in conjunction with a replay of the log file, to recover the database without any loss of data, providing the log file was not lost.


Switching From Full To Simple Recovery Models


While switching from full to simple recovery will allow you to reclaim disk space, it will also break the backup log chain. To deal with this, Embotics strongly recommends that you backup the log immediately prior to making the change, which will then allow you to restore the database up to that point. After making the switch you will need to take periodic backups to protect your data and to truncate the inactive portion of the transaction log.

Follow the procedure below to switch your Embotics vCommander database between full and simple recovery.

  1. Login to a computer where SQL Server Management Studio is installed.
  2. Launch SQL Management Studio from the Start menu.
  3. Choose Database Engine as the Server type, choose the correct Server Name from the list or browse for the correct server.


    If your user account has rights to access the database, leave Authentication as Windows Authentication. Otherwise, switch it to SQL Server Authentication and enter the User name and Password for a SQL account with rights to access the database.
    Note: If you are not sure which account to use, you can confirm what’s being used by Embotics vCommander by opening the vCommander Control Panel.
  4. Click Connect.
  5. Expand Databases, right-click your Embotics vCommander database and select Properties.
  6. Switch to the Options page and select Simple as the recovery model and click OK.

See Also