Dell POWERVAULT MD3600I - Manual (Page 154)

Scheduling A Snapshot Virtual Disk
When you create a snapshot virtual disk, you can choose whether the snapshot is created immediately or is created
according to a schedule that you determine. This schedule can be a one-time snapshot creation or an snapshot creation
that occurs at regularly occurring intervals. If a schedule is not specified, the snapshot virtual disk creation happens
immediately upon execution of the command.
A schedule can be specified when a snapshot virtual disk is first created, or it can be added to an existing snapshot
virtual disk at any time. One schedule per snapshot virtual disk is supported.
Common Reasons For Scheduling A Snapshot Virtual Disk
Scheduling a snapshot virtual disk can serve multiple purposes across a data storage environment. Most common uses
of a snapshot scheduler are:
• Data backups
• Rapid recovery from a data loss event
A scheduled data backup can protect against data loss on a regular, unmonitored basis. For example, if an application
stores business-critical data on two virtual disks in the storage array, you may choose to perform an automatic backup
every day. To implement this backup, select the first virtual disk and create a backup schedule that runs once a day,
Monday through Friday, at a time between the end of the work day and 11PM. Do not select an end date. Apply the same
schedule to the second virtual disk, then map the two snapshot virtual disks to your backup host server and perform
your regular backup procedures. Remember to unmap the two resulting snapshot virtual disks before the next scheduled
snapshot begins. If the snapshot virtual disks are not unmapped, the storage array does not perform the next scheduled
snapshot operation in order to avoid data corruption.
Scheduled snapshots are also valuable in the event of a data loss. For example, if you back up your data at the end of
every work day and keep hourly snapshots from 8AM to 5PM, data can be recovered from the snapshots in windows
smaller than one hour. To accomplish this type of rapid recovery, create a schedule that contains a start time of 8AM
and an end time of 5PM, then select 10 snapshots per day on Monday through Friday with no end date.
Guidelines for Creating Snapshot Schedules
Certain guidelines apply when creating snapshot virtual disk schedules:
• Scheduled virtual disk snapshot operations do not occur if:
– The snapshot virtual disk is mapped
– The storage array is offline or turned off
– The snapshot virtual disk is in use as a source virtual disk during a Virtual Disk Copy operation
– A copy operation is Pending or In progress
• Deleting a snapshot virtual disk that contains a schedule also deletes the schedule.
• Snapshot schedules are stored in the configuration database on the storage array. The Management Station
does not need to be running for scheduled snapshot operations to occur.
• Snapshot schedules can be created when the snapshot virtual disk is initially created or can be added to
existing snapshot virtual disks.
Creating A Snapshot Virtual Disk Using The Simple Path
You can choose the simple path to create a snapshot virtual disk if the disk group of the source virtual disk has the
required amount of free space. A snapshot repository virtual disk requires a minimum of 8 MB free capacity. The
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