Volume Size Considerations For Rmc (Pprc) - IBM System storage DS6000 Series Redbook

Figure 29-1 Add 2105 Copy Services Domain
6. Enter the IP address of the ESS Copy Services server A in the Server 1 IP field. If you
have a Server B, select Define a second Copy Services server and enter the Server B
IP address in the Server 2 IP address. However, if Server B is running on a 2105-F20, you
should not define it.
Having added the ESS 800 Copy Services domain to the DS GUI, you are now able to use
the DS GUI to create paths and RMC pairs, where the ESS 800 is the source device. You can
also use the DS GUI to manager FlashCopy pairs on the ESS 800.
Note: The steps to add the ESS 800 Copy Services Domain to a DS6000 cannot be
performed using the DS CLI. However if you do not plan to use the GUI, this is not an
issue.
Restriction: You cannot use the ESS Copy Services Server Web GUI to manage Copy
Services relationships between an ESS 800 and a DS6000. The Volumes tab only shows
ESS 800 volumes, not DS6000 volumes. The Paths tab does not show paths between an
ESS 800 and a DS6000. It only shows paths between ESS 800s. If you are using PPRC
between a DS6000 and an ESS 800, all management of that PPRC relationship must be
done with DS CLI or via the DS GUI.
Storage management
You cannot use the DS6000 DS GUI to perform storage configuration on an ESS 800.
Likewise you cannot use the ESS 800 Web Specialist to perform storage configuration on a
DS6000. You can only perform Copy Services management tasks on the alternative device. If
you are logged on to the DS6000 DS GUI and wish to configure some storage on the ESS
800, you must log on to the ESS 800 Web Specialist.

29.2.7 Volume size considerations for RMC (PPRC)

When using PPRC to copy the contents of a CKD volume from one storage device to another,
it is possible for the PPRC target volume to be larger than the PPRC source volume.
However, if an attempt is made to reverse the relationship so that the source becomes the
target, then this attempt will fail because the source is now larger than the target. For this
reason it is always recommended that the source and target volumes be the same size. Prior
to creating a PPRC relationship, check the volumes sizes to ensure they are the same for
each storage device.
Determining DS6000 and DS8000 CKD volume size
When CKD volumes are created on a DS6000 or DS8000, the size must be specified in
cylinders. In Example 29-3, two CKD volumes of 3339 cylinders are created. This means that
Chapter 29. Interoperability between DS6000 and ESS 800
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