Clone And Snapshot Trade-Offs - EMC CX700 Planning Manual

Clone and Snapshot Trade-offs

Table 4-2
Clones
Benefits • Provides enhanced protection against critical data loss
because it is an actual LUN.
• Provides immediacy in replacing the contents of the
source LUN with the contents of the clone LUN, should
the source become corrupted.
• Provides immediacy in redirecting hosts from the
source LUN to the clone LUN, should the source
become corrupted.
• Makes backup operation of a clone nondisruptive.
Creation Time Minutes to hours. The creation time depends on the size of
the source LUN.
Disk Space Uses the same amount of disk space as the source LUN.
Used
Data Recovery Instantaneous after initializing a reverse synchronization.
Time After
Source LUN
Failure/
Corruption
Performance • There is no performance impact when a clone is in a
Impact on the fractured state.
Storage System
• For the initial synchronization of the clone,
performance decreases. Subsequent synchronizations
have minimal impact on performance.
• For synchronizations and reverse synchronizations, the
performance decrease is the same as an initial
synchronization but for a shorter period of time. Impact
is also determined by the synchronization rate, which is
set when the clone is added to the Clone Group.
The following table describes the benefits and trade-offs of using
clones, snapshots, and snapshots of clones.
A Comparison of Clones and Snapshots
Data Replication and Data Mobility Software
Snapshots Snapshots of Clones
Provides a quick and Provides an extra level of
instant copy because protection against critical
it is a virtual LUN data loss if both the
(provided that the source LUN and clone
snapshot is used in LUN become corrupted.
conjunction with a
backup operation).
Instantaneous Instantaneous
Uses reserved LUN Uses reserved LUN pool
pool space, which is space (for the snapshot)
usually 10% to 20% and full disk space (for
of the source LUN the clone), which usually
size, but will vary totals 110% to 120% of
depending on how the source LUN size, but
much data has will vary depending on
changed on the how much data has
source LUN. changed on the source
LUN.
Restore time from Restore time from
network or backup network or backup tape if
tape. fractured clone received
host I/O.
A slight performance Combination of both
decrease due to the clones and snapshots.
copy-on-first-write.
What Is SnapView?
4-7