How to enable verbose log mode on Sharepoint 2010

First Method: Using Central Administration

1) Open your Central Administration
2) Click Monitoring and Click “Configure Diagnostic Logging”

3) Select “All Categories” and
Select “Verbose” for “Least critical event to report to the event log”
Select “Verbose” for “Least critical event to report to the trace log”

4) Click Ok.

Important!:Please don’t forget change mode to default after collecting needed verbose mode logging. Because in verbose mode log files grows rapidly and if you are not enough storage your sharepoint server would be crashed.

Important!:Before enabling verbose mode ensure you have enough hdd space on ALL your servers. Because this is a farm configuration and all servers has been affected by this change.

For more information about levels :

Second Method: Using PowerShell

  1. Verify that you meet the following minimum requirements: See Add-SPShellAdmin.
  2. On the Start menu, click All Programs.
  3. Click Microsoft SharePoint 2010 Products.
  4. Click SharePoint 2010 Management Shell.
  5. At the Windows PowerShell command prompt (that is, PS C:\>), type the following command, and then press ENTER:Set-SPLogLevel -TraceSeverity {None | Unexpected | Monitorable | Medium | High | Verbose} -EventSeverity {None | Information | Warning | Error | Critical | Verbose} [-Identity <Category name…>]  -VerboseYou can use the Identity parameter to specify one or more categories to change — for example, Administration. If you do not specify the value for the Identityparameter, all categories are changed.To view the current settings, type Get-SPLogLevel, and then press ENTER.To set all categories back to default levels, type Clear-SPLogLevel, and then press ENTER.

For Example set all logs to verbose use fallowing command:
Set-SPLogLevel  -TraceSeverity Verbose -EventSeverty Verbose

You can find Sharepoint logs in folder: (Default folder)
Drive:\Program Files\Common Files\Microsoft Shared\Web Server Extentions\14\LOGS
NOTE: If you need to transfer these files to Microsoft File Services , please compress files in zip file. If zip file size is bigger than  5GB please spearate multiple files that lower than 5GB.

Please read Logging Best Practices from MSDN

The SharePoint Server 2010 environment might require configuration of the diagnostic loggings settings after initial deployment or upgrade and possibly throughout the system’s life cycle. The guidelines in the following list can help you form best practices for the specific environment.

  • Change the drive that logging writes to. By default, diagnostic logging is configured to write logs to the same drive and partition that SharePoint Server 2010 was installed on. Because diagnostic logging can use lots of drive space and writing to the logs can affect drive performance, you should configure logging to write to a drive that is different from the drive on whichSharePoint Server 2010 was installed. You should also consider the connection speed to the drive that logs are written to. If verbose-level logging is configured, lots of log data is recorded. Therefore, a slow connection might result in poor log performance.
  • Restrict log disk space usage. By default, the amount of disk space that diagnostic logging can use is not limited. Therefore, limit the disk space that logging uses to make sure that the disk does not fill up, especially if you configure logging to write verbose-level events. When the disk restriction is used up, the oldest logs are removed and new logging data information is recorded.
  • Use the Verbose setting sparingly. You can configure diagnostic logging to record verbose-level events. This means that the system will log every action that SharePoint Server 2010 takes. Verbose-level logging can quickly use drive space and affect drive and server performance. You can use verbose-level logging to record a greater level of detail when you are making critical changes and then re-configure logging to record only higher-level events after you make the change.
  • Regularly back up logs. The diagnostic logs contain important data. Therefore, back them up regularly to make sure that this data is preserved. When you restrict log drive space usage, or if you keep logs for only a few days, log files are automatically deleted, starting with the oldest files first, when the threshold is met.
  • Enable event log flooding protection. Enabling this setting configures the system to detect repeating events in the Windows event log. When the same event is logged repeatedly, the repeating events are detected and suppressed until conditions return to a typical state.