Administrator Guide

For example, assume you have a collection for which the active pool is Pool-A and the alternate pool is Pool-B, and Pool-C is a
third pool in the group. Any synchronous replication-enabled volumes that use Pool-C must have their pool assignments changed
to be using Pool-A and Pool-B before they can be added to the collection.
• When you create the collection, active and alternate pools for the collection’s volumes are chosen based on the pool assignment
of the rst volume added to the collection. If you create the collection with the GUI, the group switches the active and alternate
pools as necessary so that all volumes in the collection have the same pool assignments. In the CLI, you must manually set the
pool assignments before creating the collection.
For example, assume you have a collection for which the active pool is Pool-A and the alternate pool is Pool-B. Any volumes that
have Pool-B for their active pool and Pool-A for their alternate pool will be switched when they are added to the collection.
NOTE: Pool switches briey take the volume oine, which might disrupt iSCSI connections to the volume.
Consequently, Dell recommends that synchronous replication volume collections should be created only during
periods of downtime or low activity.
• You can pause synchronous replication for one volume in the collection or for the entire collection. If you pause synchronous
replication for a single volume in the collection, the sychronous replication status of all other volumes in the collection is also
shown as out of sync, even though data is still written to their active and alternate pools. The system brings the collection back
in sync after synchronous replication is resumed for all volumes.
About Using Thin Clones and Templates with Synchronous Replication
If you are going to use synchronous replication with thin clones and template volumes, the following restrictions and considerations
apply.
Thin Clones
• When you create a thin clone of a template volume for which synchronous replication is enabled, the thin clone resides in the
template volume’s active pool.
• You must manually enable synchronous replication for thin clones. Synchronous replication is not automatically enabled for the
thin clones of a synchronous replication-enabled template.
• You can enable synchronous replication for a thin clone if the following conditions are met:
– Synchronous replication is enabled for the thin clone’s template.
– The initial copy of the template’s data from the active pool to the alternate pool has completed.
• All thin clones of a template volume must reside in the same pools as the template. However, their active and alternate pool
assignments might dier.
For example, a template volume might have PoolA for its active pool and PoolB for its alternate pool. Any or all of its thin
clones might have
PoolB for its active pool and PoolA for its alternate pool.
• Performing a switch on a thin clone neither switches the pools of any other thin clones that share the same template, nor
switches the template’s pools.
• Disabling synchronous replication for a thin clone does not change the synchronous replication conguration of its template, or
that of any other thin clones that share the template.
Templates
• You cannot switch the pool of a template until the initial copy of the template’s data from the active pool to the alternate pool
has completed.
• If synchronous replication is enabled for a template volume, you can detach one of its thin clones at any time, provided that both
the active and alternate pools are available. If they are not available, you must disable synchronous replication for the thin clone
before detaching it.
• You can convert a synchronous replication template back into a volume only when the following conditions are met:
– The initial data copy from the SyncActive volume to the SyncAlternate volume has completed.
– The active and alternate pools are available. If they are not both available, you must disable synchronous replication for the
template before performing the conversion.
• Before disabling synchronous replication for a template, you must rst disable synchronous replication for each of its thin clones.
• If you disable synchronous replication on a template, a copy of the template remains in the alternate pool.
About Synchronous Replication
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