Please enable JavaScript.
Coggle requires JavaScript to display documents.
ISDM - 12 Local Replication - Coggle Diagram
ISDM - 12
Local Replication
Used for
Backup
Decision Support Activities
Testing
Consistency
Offline
FS
Unmount
DB
Shutdown
Online
FS
Flush host buffer
DB
Dependent Write I/O
Holding I/O
Technologies
Host-based
LVM Based
Writes to a logical volume written to two physical volumes.
More host overhead
Performance Decrease
Not used alongside RAID
File System Snapshot
Pointer-based replication
Copy on First Write (CoFW) principle
Fraction of the space usage.
Same characteristics as LVM based.
(Host overhead etc.)
Storage Array Based
Performed by the Array.
Source & replica on same array
Types
Full-volume mirroring
Process
Copy Data
Final Sync
Attach target to source
Detach Target
High storage usage
Not suitable when less number of writes to source
Pointer-based full-volume
replication
Target immediately available once replication started.
No synchronization & detachment
Modes
Full copy mode
All data copied to target in background.
Copy on First Access
When data is copied
Writes on Source
Writes on Target
Read on Target
Pointer-based virtual replication
Target does not hold data.
Holds pointers only.
Target Immediately accessible.
Copy on First Write
Writes to the source
Writes to the Target
Recommended
Read requests served from the source.
Network Based
At Network Layer
Between host & storage arrays.
Benefits
Array based benefits
Host Based Benefits
Continuous Data Protection
Write Splitter
CDP Appliance
CDB Journal
Keeps track of changes
(For point-in-time recovery)
Replica
Tracking Changes
AIT --> Target OR Source
1 --> Changed
0 --> Unchanged
On Virtualized Envs
Storage Level
LUN replicated to another.
Compute Level
Performed by hypervisor