Unknown Error - Sharepoint Search - Sharepoint 3.0

Question

We're recieving an unknown error performing any search on sharepoint. I'm also getting an error when accessing the "Manage Search Service" tool. Here is our recent log. I'm not sure what to look at.
01/08/2014 09:00:32.63  wmiprvse.exe (0x12A0)                    0x5524 ULS Logging                  
 Unified Logging Service        8wsw High     Now terminating ULS (wmiprvse.exe, Microsoft.Office.Server.Native.dll) 
01/08/2014 09:00:32.63  wmiprvse.exe (0x12A0)                    0x5524 ULS Logging                  
 Unified Logging Service        8wsw High     Now terminating ULS (wmiprvse.exe, onetnative.dll) 
01/08/2014 09:00:32.78  wmiprvse.exe (0x12A0)                    0x5524 ULS Logging                  
 Unified Logging Service        8wsv High     ULS Init Completed (wmiprvse.exe, Microsoft.Office.Server.Native.dll) 
01/08/2014 09:00:32.80  wmiprvse.exe (0x12A0)                    0x5524 ULS Logging                  
 Unified Logging Service        8wsv High     ULS Init Completed (wmiprvse.exe, onetnative.dll) 
01/08/2014 09:00:34.59  OWSTIMER.EXE (0x324C)                    0x2E10 SharePoint Portal Server       Business Data                
 7pkf Monitorable Portal Analytics processing job started. 
01/08/2014 09:00:34.59  OWSTIMER.EXE (0x324C)                    0x2E10 SharePoint Portal Server       Business Data                
 7pkg Monitorable Portal Analytics processing job finished. 
01/08/2014 09:01:04.66  OWSTIMER.EXE (0x324C)                    0x389C Windows SharePoint Services    E-Mail                       
 6871 Information The Incoming E-Mail service has completed a batch.  The elapsed time was 00:00:00.  The service processed 0 message(s) in total. 
01/08/2014 09:02:04.70  OWSTIMER.EXE (0x324C)                    0x6FAC Windows SharePoint Services    E-Mail                       
 6871 Information The Incoming E-Mail service has completed a batch.  The elapsed time was 00:00:00.  The service processed 0 message(s) in total. 
01/08/2014 09:02:22.06  w3wp.exe (0x39B8)                        0x61BC ULS Logging                  
 Unified Logging Service        8wsv High     ULS Init Completed (w3wp.exe, Microsoft.Office.Server.Native.dll) 
01/08/2014 09:02:22.11  w3wp.exe (0x39B8)                        0x61BC Windows SharePoint Services    General                      
 8dzz High     Exception Type: System.NullReferenceException  Exception Message: Object reference not set to an instance of an object.  
01/08/2014 09:03:32.04  mssearch.exe (0x666C)                    0x6E04 Search Server Common           GatherSvc                    
 0 Monitorable TraceHealthStatus application '4892d77b-b5df-4880-a0a5-99b8ec963264': 63085 seconds since last status request from timer service;  - File:d:\office\source\search\search\gather\gthrsvc\gthrapp.cxx Line:5890 

Answer 1

The answer is Yes, and you are correct about the best practice of a limit of 100GB,
although, document and record centers (e.g. non collaborative) can go much higher.
http://technet.microsoft.com/en-us/library/cc262787(v=office.15).aspx#ContentDB
That being what it is, your sites will perform better if you find a topology that allows the content databases to be under 100GB each.  You can use Move-SPSite to accomplish that feat.
You'll want a separate instance for 2010 and a separate instance for 2013
and finally, put some quota's in place and then governance document\statement that informs users that 100 GB is the max for any given site collection that uses collaborative features (calendars, lists, workflows, etc.)
The simple path is explained on technet, go from 2007 to 2010 (you can inplace upgrade if you want) then go from 2010 to 2013, database detach and attach is only way.
please check the below link that explains more about the migration from share point 2007->2013.
http://technet.microsoft.com/en-us/library/cc262483(v=office.15)
Stacy www.sharepointpapa.com