Snapshot Space - Overland Storage SnapServer Administrator's Manual

SnapServer 7.0 Administrator's Guide
Each directory inside the snapshot share represents a different snapshot. The directory
names reflect the date and time the snapshot was created. However, the
always points to the latest snapshot (in this case, 2011-10-07.020200, or October 7th,
2011, at 2:02 a.m.). In this case, configuring the backup software to copy from:
\SHARE1_SNAP\latest
ensures that the most recently created snapshot is always archived.

Snapshot Space

Snapshots are stored in a RAID set or storage pool in snapshot space reserved within the
RAID set for this purpose. Each RAID set on the system contains its own independent
snapshot space. This space contains all snapshot data for all the volumes on the RAID set
or storage pool.
Estimating Snapshot Space Requirements
Snapshot data grows dynamically for as long as a snapshot is active and as long as there is
enough space available in the snapshot space to store them. When the snapshot space
approaches its capacity (at about 95 percent), the SnapServer deletes the oldest snapshot's
data to create space for more recent snapshot data.
By default, 80 percent of RAID set or storage pool capacity is allocated to volumes and 20
percent to snapshot space. You can adjust the amount of snapshot space on the RAID set or
storage pool up (assuming unallocated space exists) or down according to your needs. If you
find that your snapshot strategy does not require all of the space allocated to the snapshot
space by default, consider decreasing snapshot space capacity and reallocating the capacity
to the Traditional RAID volumes or data storage in the DynamicRAID storage pool.
Adjusting Snapshot Space Size
The size of the snapshot space can be adjusted at any time. However, under DynamicRAID,
to increase the size of the space a new disk drive must be added to the Storage Pool.
To adjust the size of the snapshot space:
• For DynamicRAID, navigate to the Storage > Storage Pools page, and then click the
Storage Pool name for the snapshot space you want to adjust. Using the drop-down
list, select the percentage of space you want to reserve on this pool.
• For Traditional RAID, navigate to the Storage > Snapshots page, click the Snapshot
Space button, and then click the RAID set name for the snapshot space you want to
adjust. Enter the new amount in the Snapshot Space field.
The number of snapshots that a RAID set can support is a function of these factors:
• The space reserved for the snapshot data.
• The duration of the snapshots you create.
• The amount and type of write activity to the volume since the snapshot was created.
The following table describes minimum and maximum allocation cases.
10400317-001 10/2011
©2010-11 Overland Storage, Inc.
6 – Other Storage Options
directory
latest
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