Dell POWERVAULT MD3620I - Manual (Page 157)

Configuration: Premium Feature—Snapshot Virtual Disks 157
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 ongoing
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.
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