hi all i have wqritten a controller and i am getting this error

Class.Group_Renewal.checkpdf: line 173, column 9 External entry point\

System.DmlException: Update failed. First exception on row 0 with id 006V00000029g8gIAA; first error: STORAGE_LIMIT_EXCEEDED, storage limit exceeded: [] 

this is my controller and i am getting the error at checkpdf() method update op plz can some one tell what exactly is this error

public with sharing class Group_Renewal
{

    public String getUncheck() {
        return null;
    }



public list<AggregateResult> lstAR = new list<AggregateResult>();
public Opportunity userInputAppointment {get; set;}
public List<Opportunity> opp99{get;set;} 
public List<Opportunity> op{get;set;} 
public Account userinputact {get; set;}
public String[] acts {get;set;}
Set<Id> tskNo = new Set<Id>();
public Task[] tsk ;
public string u;
public string countopp{get; set;}
Set<String> temp = new Set<String>();



public list<AggregateResult> lstARdel = new list<AggregateResult>();
public List<Opportunity> opdel{get;set;} 
public String[] actsdel {get;set;}

  
 public Group_Renewal()
{
 
userInputAppointment = new Opportunity();
userinputact = new Account();
 
userInputAppointment.From_Date__c=Date.valueof(ApexPages.currentPage().getParameters().get('fromdate'));
userInputAppointment.To_Date__c=Date.valueof(ApexPages.currentPage().getParameters().get('todate'));
userinputact.Search_By_Name__c=ApexPages.currentPage().getParameters().get('cha');
countopp=ApexPages.currentPage().getParameters().get('countopp');

 //Retrieving the Activities(Tasks)
 tsk=[select  whatid from task  where Priority='Renewal' and ActivityDate>=:userInputAppointment.From_Date__c and  
 ActivityDate<=:userInputAppointment.To_Date__c ]; 
 

for(Task aa: tsk)
{
tskNo.add(aa.whatid);
} 



// Spliting the user input for search cretiria.
u=userinputact.Search_By_Name__c;


String[] result=u.split('\\,');

for( Integer i = 0; i<result.size(); i++)
        {
            temp.add(result[i]+'%');
        }



//Retrieving the opportunities and account fileds
op = [select id,name,Total__c,Account.Name,Account.Director_ID__c,Start_Issue_Qtr__c,Expire_Issue_Qtr__c,Opp_Check_to_PDF__c,
Renewal_Effort__c,Account.Bill_To__r.Name,Account.Bill_To__r.Id from Opportunity where id in:tskNo and
recordType.id=:'012V0000000CgYl' and  Account.Bill_To__r.Name!='' and Account.Bill_To__r.Name LIKE:temp  order by Account.Bill_To__r.Name];


//this query for getting Amount(SUM) on to visual force page after Grouping.
lstAR = [Select Sum(Total__c)am,Account.Bill_To__r.Id ocn,Account.Bill_To__r.Bank_Mailing_PDF__c p from Opportunity  where id in:op and
recordType.id=:'012V0000000CgYl' and Account.Bill_To__r.Name LIKE:temp   Group By Account.Bill_To__r.Id,Account.Bill_To__r.Bank_Mailing_PDF__c];
 

Set<String> stateSet = new Set<String>();
 for(Opportunity a : op)


 stateSet.add(a.Account.Bill_To__r.id);
  //stateSet.add(a.name);
 
   acts = new String[stateSet.size()];
  Integer i = 0;
   
    for (String state : stateSet)
     { 
      acts[i] = state;
      i++;
     }
     acts.sort();
 
   
   
   
   opdel = [select id,name,Total__c,Account.Name,Account.Director_ID__c,Start_Issue_Qtr__c,Expire_Issue_Qtr__c,Opp_Check_to_PDF__c,
Renewal_Effort__c,Account.Bill_To__r.Name,Account.Bill_To__r.Id from Opportunity where id in:tskNo and
recordType.id=:'012V0000000CgYl' and Opp_Check_to_PDF__c=true and  Account.Bill_To__r.Name!='' and Account.Bill_To__r.Name LIKE:temp  order by Account.Bill_To__r.Name];


//this query for getting Amount(SUM) on to visual force page after Grouping.
lstARdel = [Select Sum(Total__c)am,Account.Bill_To__r.Id ocn,Account.Bill_To__r.Bank_Mailing_PDF__c p from Opportunity  where id in:op and
recordType.id=:'012V0000000CgYl' and  Opp_Check_to_PDF__c=true and  Account.Bill_To__r.Name!='' and Account.Bill_To__r.Name LIKE:temp   Group By Account.Bill_To__r.Id,Account.Bill_To__r.Bank_Mailing_PDF__c];
 

Set<String> stateSetdel = new Set<String>();
 for(Opportunity adel : opdel)


 stateSetdel.add(adel.Account.Bill_To__r.id);
  //stateSet.add(a.name);
 
   actsdel = new String[stateSetdel.size()];
  Integer idel = 0;
   
    for (String statedel : stateSetdel)
     { 
      actsdel[idel] = statedel;
      idel++;
     }
     actsdel.sort();
 
     
   
   
   
   
   
}



// for displaying Amount(Sum)
    public list<Opp> getResult()  
    {  
    list<Opp> lstResult1 = new list<Opp>();  
    for (AggregateResult ar: lstAR)  
    {
    opp objOpp= new opp(ar);  
    lstResult1.add(objOpp);  
    }  
    return lstResult1;  
    }  


// for "opp" which is used in above getResult 
class opp
{  
public Double am{ get;set; }
 
public string p{ get;set; }
public string ocn{ get;set; }


public opp(AggregateResult ar)  
{  
am = (Double)ar.get('am');
ocn = (string)ar.get('ocn');  
p = (string)ar.get('p');
}
}


 public PageReference deliverAsPDF()
  {   
        PageReference pdf = new PageReference('/apex/Group_Renewal_PDF');   
        pdf.getParameters().put('p','p');
        return pdf;
  }

 public PageReference checkpdf()
  {   
        update op;
        PageReference pdfdel = new PageReference('/apex/Group_renewal_checkbox');   
        pdfdel.getParameters().put('p','p');
        return pdfdel;
  }
  public void uncheck()
  {
      for(opportunity opps1:op)
      {
      if(opps1.Opp_Check_to_PDF__c==true)
      {
       opps1.Opp_Check_to_PDF__c=false;
       
      }
     
      
          
      }
 
  
   
  } 




}