How to best upgrade the HDDs in a MD3000i in production?

We have an MD3000i that is completely filled with 300 GIG SAS drives and we are running out of HDD space.

I believe my options are to add an MD1000 or to upgrade the MD3000i with bigger 2 TB Hdd's.  

I want to avoid adding any more hardware to the Rack to save on space and Amps usage (if possible)

My question is:

1. can i safely do a "replace" one Hdd at a time with a larger 2TB SATA drives and let the raid rebuild, then replace another drive....and so on until all drives are replaced with higher 2 TB drives?  then will the Raid recognize the extra space after all disks are upgraded?  I'm not sure if i can mix SATA with SAS?

2. do you recommend a different approach to solve my need for increased NAS capacity on the existing MD3000i ?

Here is my HDD config from the Powervault MD3000i:

THANKS for your help!!

PROFILE FOR STORAGE ARRAY: MD3000ix01 (Wed Dec 14 18:21:45 EST 2011) 
 
 
DISK GROUPS------------------------------ 
 
   Number of disk groups: 3 
 
 
   Name:                          1                                  
                                                                     
      Status:                     Optimal                            
                                                                     
      Capacity                    278.896 GB                         
      RAID level:                 1                                  
                                                                     
      Physical Disk type:         Serial Attached SCSI (SAS)         
      Enclosure loss protection:  No                                 
                                                                     
      Current owner:              RAID Controller Module in slot 0   
 
 
      Associated virtual disks and free capacity 
 
 
         Virtual Disk  Capacity        
            LUN1          1.000 GB     
            LUN2          277.896 GB   
                                       
 
 
      Associated physical disks - present (in piece order) 
 
 
         Enclosure     Slot                                                             
            0             0 [mirrored pair with physical disk at enclosure 0, slot 1]   
            0             1 [mirrored pair with physical disk at enclosure 0, slot 0]   
 
 
 
 
   Name:                          2                                    
                                                                       
      Status:                     Optimal                              
                                                                       
      Capacity                    1.634 TB                             
      RAID level:                 5                                    
                                                                       
      Physical Disk type:         Serial Attached SCSI (SAS)           
      Enclosure loss protection:  No                                   
                                                                       
      Current owner:              RAID Controller Module in slot 0,1   
 
 
      Associated virtual disks and free capacity 
 
 
         Virtual Disk      Capacity        
            LUN4              1.000 TB     
            LUN3              370.483 GB   
            LUN5              139.000 GB   
            Free Capacity     139.896 GB   
                                           
 
 
      Associated physical disks - present (in piece order) 
 
 
         Enclosure     Slot   
            0             2   
            0             3   
            0             4   
            0             5   
            0             6   
            0             7   
            0             8   
 
 
 
 
   Name:                          3                                    
                                                                       
      Status:                     Optimal                              
                                                                       
      Capacity                    1.089 TB                             
      RAID level:                 5                                    
                                                                       
      Physical Disk type:         Serial Attached SCSI (SAS)           
      Enclosure loss protection:  No                                   
                                                                       
      Current owner:              RAID Controller Module in slot 0,1   
 
 
      Associated virtual disks and free capacity 
 
 
         Virtual Disk  Capacity        
            LUN6          300.000 GB   
            LUN7          80.000 GB    
            LUN8          2.000 GB     
            LUN9          733.586 GB   
                                       
 
 
      Associated physical disks - present (in piece order) 
 
 
         Enclosure     Slot    
            0             9    
            0             10   
            0             11   
            0             12   
            0             13