IBM DS8000 - Manual (Page 323)

Chapter 14. Data migration in zSeries environments 301
Most of these benefits also apply to migration efforts controlled by the customer when utilizing
TDMF or FDRPAS in customer-managed systems.
Piper for z/OS is an IGS service offering which relieves the customer of the actual migration
process and requires customer involvement only in the planning and preparation phase. The
actual migration is transparent to the customer’s application hosts and Piper even manages a
concurrent switch-over to the target volumes. Piper is neutral to the disk storage vendors and
works for all devices supported under z/OS or OS/390.
Data migration with z/OS Global Mirror
Another alternative is z/OS Global Mirror (XRC). XRC is an asynchronous solution that has a
mode for disaster recovery (DR) solutions as well as a particular migration mode of
SESSIONTYPE(MIGRATE). This mode does not require the customer to plan for a
JOURNALs configuration at the secondary site, which is mandatory for DR solutions based
on XRC.
Figure 14-3 Data Migration with z/OS Global Mirror (XRC)
XRC allows for an online data migration approach, which is almost non-disruptive. The
application only needs to shut down for the actual switch to the target volumes in the new disk
storage server. It can restart immediately to connect to the new disk storage server after the
XRC secondary volumes have been relabeled by a single XRC command per XRC session,
XRECOVER.
In addition to transparent data replication, the advantage of XRC is extreme scalability.
Figure 14-3 shows that XRC can run either in existing system images or in a dedicated LPAR.
Each image can host up to five System Data Movers (SDM). An SDM is an address space
(ANTAS00x) that is started by a respective XSTART command. A reasonable number of XRC
volume pairs that a single SDM can manage is in the range of 1,500 to 2,000 volume pairs.
With up to five SDMs within a system image, this totals approximately 10,000 volume pairs.
Production systems
OS/390
zOS
zLINUX
zVM
VSE/ESA
no minidisks
Director
ESCON / FICON
ANTAS002
SDM LPAR
XRECOVER
SDM1 SDM2
SDM3
SDM5
SDM4 XRECOVER XRECOVER
XRECOVER XRECOVER
Primary
Volume
Secondary
Volume
Source
Disk
subsystems
Target
Disk
Servers
ANTAS001
ANTAS003
ANTAS004
ANTAS004