Administrator Guide

Table Of Contents
Live Volume After Swap Role
In the following diagram, a role swap has occurred so the secondary Storage Center is on the left and the primary Storage
Center is on the right.
Figure 48. Example Live Volume Configuration After Swap Role
1. Server 2. Server IO request to secondary volume (forwarded to
primary Storage Center by secondary Storage Center)
3. Secondary volume 4. Live Volume replication over Fibre Channel or iSCSI
5. Primary volume 6. Server IO request to primary volume over Fibre Channel or
iSCSI
7. Server
Automatic Swap Role for Live Volumes
Live Volumes can be configured to swap primary and secondary volumes automatically when certain conditions are met to avoid
situations in which the secondary volume receives more IO than the primary volume.
Attributes that Control Swap Role Behavior
When automatic swap role is enabled, the following limits determine when a role swap occurs.
Swap Role Limit
Description
Min Amount Before Swap Specifies the minimum amount of storage space that must be written
to the Live Volume on the secondary Storage Center before the roles
can be swapped
Min Time As Primary Before Swap (Minutes) Specifies the number of minutes that must pass before the roles can
be swapped.
Min Secondary Percent Before Swap (%) Specifies the minimum percentage of IO that must take place on the
secondary volume before the roles can be swapped.
Triggering an Automatic Swap Role
For an automatic swap role to occur, the following events must take place.
Steps
1. The Automatically Swap Roles feature must be enabled for the Live Volume.
2. The timeout specified in the Min Time As Primary Before Swap (Minutes) field must expire.
3. Over a five minute period, one of the following limits must be exceeded for least 70% of the samples conducted during that
time.
Min Amount Before Swap
520
Storage Center Replications and Live Volumes