Hi

I have a site running with Umbraco 4.0.3 at MySQL and mostly uses XSLT. It has around 2000 nodes in the content tree with a max of 50 nodes in subnodes.

The site has been running fine for a long time, but within the last month IIS crashes more and more often, at the moment 1-2 times every 24 hours. 

IIS returns "Service unavailable" and scheduled AppPool recycles don't solves the problem.

The last time IIS was reset, I got this error on publish (Umbraco worked again after a couple of more IIS resets):

'Error Republishing: umbraco.DataLayer.SqlHelperException: Umbraco Exception (DataLayer): SQL helper exception in ExecuteReader ---> MySql.Data.MySqlClient.MySqlException: Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.

   at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader(CommandBehavior behavior)

   at MySql.Data.MySqlClient.MySqlHelper.ExecuteReader(MySqlConnection connection, MySqlTransaction transaction, String commandText, MySqlParameter[] commandParameters, Boolean ExternalConn)

   at MySql.Data.MySqlClient.MySqlHelper.ExecuteReader(String connectionString, String commandText, MySqlParameter[] commandParameters)

   at umbraco.DataLayer.SqlHelpers.MySql.MySqlHelper.ExecuteReader(String commandText, MySqlParameter[] parameters)

   at umbraco.DataLayer.SqlHelper`1.ExecuteReader(String commandText, IParameter[] parameters)

   --- End of inner exception stack trace ---

   at umbraco.DataLayer.SqlHelper`1.ExecuteReader(String commandText, IParameter[] parameters)

   at umbraco.content.LoadContentFromDatabase(Boolean loadDocuments)'

Any recommendations how to find/fix a problem like that? Or is it a problem with old Umbraco's and MySQL when having "lots" of nodes/content?

Thanks in advance

Ivan