IBM XIV Storage System Copy Services and Migration

8.9.6 Removing the VDisk copyNow that the sync is complete, we can remove copy 0 from the VDisk so that the VDiskcontinues to use only copy 1 (which should be on the XIV). We have two methods ofachieving this. We can either split the copies or we can just remove one copy.Removing a VDisk copyIn Example 8-46, we remove copy 0 from VDisk 5. This effectively discards the VDisk copy onthe source MDisk group. This is simple and quick but has one disadvantage, which is that youmust mirror the data back if you decide to back out the change.Example 8-46 Removing VDisk copyIBM_2145:SVCSTGDEMO:admin>svctask rmvdiskcopy -copy 0 5Splitting the VDisk copiesIn Example 8-47 we split the VDisk copies, moving copy 0 (which is on the source MDiskgroup) to become a new unmapped VDisk. This means that copy 1 (which is on the target XIVMDisk group) continues to be accessed by the host as VDisk 5. The advantage of doing thisis that the original VDisk copy remains available if we decide to back out (although it may nolonger be in sync once we split the copies). An additional step is needed to discreetly deletethe new VDisk that was created when we performed the split.Example 8-47 Splitting the VDisk copiesIBM_2145:SVCSTGDEMO:admin>svctask splitvdiskcopy -copy 0 -name mgrate_old 5Virtual Disk, id [6], successfully createdImportant: Scripts that use VDisk names or IDs should not be affected by the use of VDiskmirroring, as the VDisk names and IDs do not change. However, if you choose to split theVDisk copies and continue to use copy 0, it will be a totally new VDisk with a new nameand a new ID.8.10 Using SVC migration with image modeThis process converts VDisks on non-XIV storage to image mode MDisks on the XIV that canthen be reassigned to a different SVC or released from the SVC altogether. Because of thisextra step, the XIV requires sufficient space to hold both transitional volumes (for image modeMDisks) and the final destination volumes (for managed mode MDisks).8.10.1 Create image mode destination volumes on the XIVOn the XIV we must create one new volume for each SVC VDisk that we are migrating (whichmust be the same size as the source VDisk, or larger). These are to allow transition of theVDisk to image mode. To do this, we must determine the size of the VDisk so that we cancreate a matching XIV volume.Chapter 8. SVC migration with XIV 267