Setup & User Guide
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DOC-246-GDE-Pivot3 Acuity 2.3 Setup & User Guide-v1.0.docx
Section 12 Snapshot Management
This chapter describes how to protect data using snapshots of volumes to create recovery points. This can be done on an
individual-volume level (manually or using schedules) or with policies to protect groups of volumes. The Data Protection
Quality of Service feature uses policies − named collections of up to three scheduled tasks − to easily apply sets of tasks to
multiple volumes.
CRITICAL:
Servers that are not added to the Protected Host list, with refreshed associations run, will not be configured to take
host-consistent snapshots.
Snapshots Overview
A SAN-based snapshot is an image of a disk at a specific point in time. Snapshots allow for basic recovery functions and
can be converted into new volumes as needed. The Protected Hosts feature allows for host consistent snapshots of
volumes on ESXI and Microsoft Windows using the Volume Shadow Copy Service (VSS) Provider.
Snapshots are thin provisioned, and as the active volume changes, previously unreferenced blocks will be kept as part of
the last snapshot. Over time, the oldest snapshot will take up additional space, with a maximum equivalent to the size of
the volume at the time the snapshot was taken.
BEST PRACTICE: Use ESXi iSCSI storage instead of guest-mounted storage.
Datastore snapshots on guest-mounted iSCSI
sessions will occasionally lose connectivity while VMware pauses the VM.
NOTE: Snapshots are not meant to replace primary backup methods.
SAN-based snapshots can be useful in the following situations:
• Snapshots can be created right before the upgrade of a system to provide an additional backup mechanism for the
environment.
• Cloned snapshots provide a mechanism to perform development or testing scenarios on an exact copy of data
without affecting production data.
Types of Snapshots
• Host Consistent: These snapshots are coordinated with the protected host to quiesce I/O before taking a snapshot,
and there is a much better chance of recovering from this type of snapshot. The Pivot3 vCenter Plugin defaults to this
type of snapshot whenever possible; if not, it relegates to Crash Consistent.
• Crash Consistent: These snapshots are not negotiated but taken at the exact moment of request, without quiescing
I/O.
NOTE: If there is not enough space on the vPG to generate a snapshot, the schedule or task returns an error:
Detected an
invalid snapshot configuration. Configure datastores and virtual disks as thin provisioned to help avoid this issue.
CRITICAL: Snapshots of datastore volumes that contain a VM using Raw Device Mapping will not be host-consistent.
Before Creating a Snapshot on Other Operating Systems
To take a restorable, host-consistent snapshot of other operating systems, the file system must be quiesced and then
synchronized before the snapshot is taken. No I/O can be running during this procedure.
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