Logical And Physical Fault; Logical Fault; Physical Fault; Backup Operation - Overland Storage Snapshot SnapSAN User Manual

SnapSAN S3000/S5000 Snapshot User Guide

Logical and Physical Fault

Logical Fault

It indicates a fault that unintended and invalid data is written to the business volume due to
an operation error or an application fault. Overwriting data or deleting necessary files
mistakenly, garbled data due to application fault etc. are the cases. A logical fault is caused
not by hardware fault but by human error or software problem.
When a logical fault occurs in the copy-source business volume, copy-destination snapshot is
not influenced. You can restore the business volume by using the snapshot created before the
fault occurred.

Physical Fault

It indicates a fault that data of the business volume is destroyed due to a hardware fault and
becomes unavailable. It requires physical restoration such as hardware exchange.
When a physical fault occurs in the copy-source business volume and data is destroyed, copy-
destination snapshot also becomes unavailable.
Volumes in the disk array are in RAID configuration, and data is not destroyed unless
multiple faults occur. In case of physical fault, however, you must restore data from other
media, not from snapshots.
Example of Applying Snapshot

Backup Operation

Backup from a snapshot to a magnetic tape medium
Backup is performed from a snapshot of a business volume to a tape or other backup media.
Data is saved from a snapshot to a tape or other backup media, and restored from a backup
medium when a business volume fault occurs.
When you back up data during normal operation, you need to stop operation only while you
create a replication volume from a business volume. Therefore, you can reduce operation
down time significantly.
10400422-002 02/2013
©2013 Overland Storage, Inc.
Logical and Physical Fault
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