Dell EMC VxFlex Ready Node, User Manual

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migration is paused due to a rebuild operation, it remains paused until the rebuild ends.
If the system encounters a communication error that prevents the migration from
proceeding, it pauses the migration and periodically tries to resume it. After a
configurable number of attempts to resume the migration, the migration remains
paused and no additional retries will be attempted. The user can manually resume
migrations that were internally paused by the system.
The system allows concurrent V-Tree migrations. These migrations are prioritized by
the order in which they were invoked, or by manually assigning the migration to the
head or the tail of the migration queue. You can update the priority of a migration
while it is being executed. The system strives to adhere to the priority set by the user,
but it is possible that volume blocks belonging to migrations lower in priority are
executed before ones that are higher in priority. This can happen when a Storage Pool
that is involved in migrating a higher priority block is busy with other incoming
migrations and the Storage Pools involved in lower priority migrations are available to
run the migration.
Snapshot Policies
Snapshot Policies enable you to define policies where you can configure the number of
snapshots to take at a given time for one or more volumes.
The snapshots are taken according to the rule defined. You can define the time
interval in-between two rounds of snapshots as well as the number of snapshots to
retain, in a multi-level structure. For example take snapshots every x minutes/hours/
days/weeks. There are one to six levels, with the first level having the most frequent
snapshots.
Example:
Rule: Take snapshots every 60 minutes
Retention Levels:
l
24 snapshots
l
7 snapshots
l
4 snapshots
After defining the parameters, you must then select the source volume to add to the
Snapshot Policy. You can add multiple source volumes to a Snapshot Policy, but a
specific volume can only be the source volume of a single policy. Only one volume per
VTree may be used as a source volume of a policy (any policy). For more information
on V-Trees, see "Snapshots" in the
Getting to Know Guide .
When you remove the source volume from the policy, you must choose how to handle
auto-snapshots. Snapshots created by the policy are referred to as auto-snapshots.
Your selection depends on if there are locked auto snapshots.
l
If the source volume has no auto snapshots, it doesn’t matter if you select Detach
auto snapshots or Remove auto snapshots.
l
If the source volume has auto snapshots but none of them are locked, you can
choose to detach all snapshots. They become regular snapshots as if the user
created them manually. If you select Remove auto snapshots, they are deleted.
l
If the source volume has locked auto snapshots, you can choose to detach all
snapshots. They become regular snapshots, as if the user created them manually.
If you remove them, those that are not locked are removed, while the auto
snapshots which are locked are detached.
Architecture
Dell EMC VxFlex Ready Node AMS User Guide 65