The wizard guides you through the steps for moving a volume to another I/O group, including any changes to hosts that are required. For more information, click Need Help  in the associated management GUI windows. 

Additional information regarding volume migrations between I/O groups can be found at IBM Knowledge Center: 

## 7.4 I/O queues 

IBM FlashSystem 9100 Knowledge Center - Managing Volumes 

Host operating system and host bus adapter software must have a way to fairly prioritize I/O to the storage. The host bus might run faster than the I/O bus or external storage. Therefore, you must have a way to queue I/O to the devices. Each operating system and host adapter have unique methods to control the I/O queue. The unique method to control I/O queue can be host adapter-based or memory and thread resources-based, or based on the number of commands that are outstanding for a device. 

You have several configuration parameters available to control the I/O queue for your configuration. The storage adapters (volumes on IBM FlashSystem 9100) have host adapter parameters and queue depth parameters. Algorithms are also available within multipathing software, such as the qdepth_enable  attribute. 

## 7.4.1 Queue depths 

Queue depth  is used to control the number of concurrent operations that occur on different storage resources. Queue depth is the number of I/O operations that can be run in parallel on a device. 

Guidance about limiting queue depths in large SANs as described in previous IBM documentation was replaced with a calculation for homogeneous and nonhomogeneous FC, iSCSI and iSER hosts. This calculation is for an overall queue depth per I/O group. You can use this number to reduce queue depths that are lower than the recommendations or defaults for individual host adapters. 

For more information, see Chapter 3, “Drives and arrays” on page 41and Queue depth in Fibre Channel hosts  topic in the V8.2 Documentation site: 

## 7.5 Host clustering and reserves 

GLYPH<SM590000> FlashSystem 9100 FC hosts Queue Depth 

IBM FlashSystem 9100 Knowledge Center - FC Queue Depth 

GLYPH<SM590000> FlashSystem 9100 iSCSI hosts Queue Depth 

IBM FlashSystem 9100 Knowledge Center - iSCSI Queue Depth 

GLYPH<SM590000> FlashSystem 9100 iSER hosts Queue Depth 

IBM FlashSystem 9100 Knowledge Center - iSER Queue Depth 

To prevent hosts from sharing storage inadvertently, establish a storage reservation mechanism. The mechanisms for restricting access to IBM Spectrum Virtualize volumes use the SCSI-3 persistent reserve commands or the SCSI-2 reserve and release commands. 

