VPLEX:  How to Set Rebuild Transfer Size

           

   Article Number:     496538                                   Article Version: 5     Article Type:    How To 
   

 


Product:

 

VPLEX Series,VPLEX Local,VPLEX Metro,VPLEX VS2,VPLEX VS6,VPLEX VS1,VPLEX GeoSynchrony 5.3,VPLEX GeoSynchrony 5.3 Patch 4,VPLEX GeoSynchrony 5.4 Service Pack 1,VPLEX GeoSynchrony 5.4 Service Pack 1 Patch 3

 

Instructions:

 

 

   

      A REBUILD WILL OCCUR WHEN       
        =========================
     
           
  •           Logging failed, mirror will be marked out of date.       
  •        
  •           whenever a new mirror is added to device, as in the case of a migration.       
  •        
  •           whenever an existing device is marked out of date.        
  •        
  •           A distributed raid-1 has one leg marked out of date due to storage issues or inter cluster link issues.       
  •        
  •           A logging rebuild will occur when a mirror (leg) of a distributed-device is removed from the source       
  •      
     
      VPlexcli:/> rebuild show-transfer-size *     This command will return transfer rate for all devices           
           
            VPlexcli:/> rebuild show-transfer-size --devices *     This command will return device name and transfer size
     
     
      device name  transfer-size         
          -----------  -------------         
          ddev_1       2M         
          ddev_10      2M         
          ddev_11      2M         
          ddev_12      2M         
          ddev_13      2M         
          ddev_7       2M         
          ddev_8       2M         
          ddev_9       2M
     
     
     
      Default       128k    This has been tested and works best         
          Max size    128M         
         
          Set the transfer-size on a specified device to 1M:           
            ======================================           
            VPlexcli:/> rebuild set-transfer-size --devices /clusters/cluster-1/devices/testdevice --limit 1M           
           
            ** alternatively:  VPlexcli:/distributed-storage/distributed-devices/DD_1234> set transfer-size 1M           
           
            setting transfer size at component level           
            ===============================           
            VPlexcli:/distributed-storage/distributed-devices/DD_1234/distributed-device-components/device_Symm1234_1234_1> set transfer-size 1M           
           
           
            Set the transfer-size for all devices to 2M:           
            VPlexcli:/> rebuild set-transfer-size /clusters/*/devices/* 2M           
           
            Set the transfer-size for all distributed devices to 10K:           
            VPlexcli:/distributed-storage/distributed-devices> rebuild set-transfer-size * 10k           
           
           
           
            Be sure to note if 'throughput' increases after increasing the transfer size.           
            It's not always the case that increasing the transfer rate will speed up the rebuilds.
   
                                                                                                                             

 

 

Notes:

 

 

   

         
  •         VPlex rebuild traffic does not do QoS and is not aware of contention /traffic.     
  •      
  •         If transfer rate is set too high, it will effect performance.     
  •      
  •         The rebuild-type should be set to full and this cannot be set manually.     
  •      
  •         If the volumes are thin provisioned then the rebuild should be thin.     
  •      
  •         If the volumes are thick provisioned then the rebuild should be thick.     
  •      
  •         The VPlex chooses the best fit rebuild type and this cannot be set manually.     
  •      
  •         It will always try to rebuild incrementally initially and if this is not possible then a full rebuild begins.     
  •    
   
    VPLEX has two types of rebuilds: full and logging.        
       
        A full rebuild will occur whenever a new mirror is added to device, as in the case of a migration, or whenever an existing device is marked out of date.        
       
        A logging rebuild will occur when a mirror (leg) of a distributed-device is removed  added from the source the VPlex will track the changes made on the blocks of the source device via the logging volume, and apply these changes to the mirror once it is re-attached.