Administrator Guide

Table Of Contents
Previous to v8.0, writing a signicant amount of data to a volume might result in the day’s replica being unusually large. The size of
this replica might be so large that older replicas are deleted from the replica set, which means that the replica set no longer retains
three replicas.
As of v8.0, replication borrowing allows replica sets to borrow enough space to hold the replicas that would otherwise be deleted. As
long as the pool has enough unused space to borrow, the replica set can borrow space to maintain the max-keep policy.
After a few days of normal I/O activity, the max-keep policy will eventually delete the large replica for which space needed to be
borrowed. The remaining replicas will probably t within the replica reserve, and the replica set might not need to borrow space any
longer.
About Cross-Platform Replication
Cross-platform replication provides a method for performing asynchronous volume replication between the PS Series groups and
Dell Storage Centers. This feature preserves the functional and operational models embodied in the current replication
implementation for each storage system. Dell Storage Manager (DSM) is the management tool for Storage Centers and it also
supports managing the PS series. DSM should be used to manage cross-platform replication as Group Manager supports read-only
view of cross-platform replication.
See the Dell Storage Manager Administrator’s Guide for detailed information about cross-platform replication using DSM.
Unsupported Functionality
Cross-platform replication does not support the following operations and components:
Replication management operations using Group Manager. Use DSM for these operations.
Manual Transfer Utility (MTU)
Host Integration Tools
Replication of VMware virtual volumes (VVols)
Replication of volume collections and NAS containers. Cross-platform replication supports volume replication only
Replication of thin clones and template volumes
Shrinking of a volume that is congured for replication if the source partner is an EqualLogic group, and the destination partner is
a Compellent array
Limitations
Group Manager no longer identies replica sets on the destination partner that do not have a corresponding volume on the
source partner. DSM provides a direct view of both partners to the same administrator.
When using cross-platform replication, volumes are automatically thin-provisioned when you promote the replica set.
Source Volume’s (network address authority) NAA IDs are not preserved on the replication volume when using cross-platform
replication.
Downgrading to an earlier version of the rmware is not allowed if a cross-platform replication partnership has been congured.
PS group volumes with a sector size of 4K bytes cannot be replicated to a Storage Center.
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