The document explains snapshots in the context of network storage as a time-specific representation of disk data, primarily used for fast and space-saving backups. It describes how snapshots function using a copy-on-write technique, allowing for data history reviews and temporary data protection, although they are not suitable for critical backups. Additionally, it discusses rollback procedures and snapshots' dependencies when deleting or reverting to earlier states.

1. Snapshots for Network Storage
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2. What is Snapshot?
- General Idea
 A “picture” of the disk, taken at a specific time point
 Used on Virtual Disks
2

3. What is Snapshot?
- General Idea
 A “picture” of the disk, taken at a specific time point
 Used on Virtual Disks
Original Snapshot 1 Snapshot 2
Timeline
3

4. What is Snapshot?
- General Idea
 A “picture” of the disk, taken at a specific time point
 Used on Virtual Disks
What is it for?
 Fast, space saving backup
 Quick review of data history
 Allows more precious restore points and frequent
backup missions
 Not suitable for critical backup purposes
 Temporary data protection when modifying data
4

5. How does it work?
- Copy on Write technique
 A space saving data backup technique that makes a
copy of the original data only if it’s modified.
5

6. How does it work?
- Copy on Write technique
 A space saving data backup technique that makes a
copy of the original data only if it’s modified.
A
Original Data (VD) Copy (Snapshot)
6

7. How does it work?
- Copy on Write technique
 A space saving data backup technique that makes a
copy of the original data only if it’s modified.
Writes B to replace A
A
Original Data (VD) Copy (Snapshot)
7

8. How does it work?
- Copy on Write technique
 A space saving data backup technique that makes a
copy of the original data only if it’s modified.
Writes B to replace A
Copy
A A
Original Data (VD) Copy (Snapshot)
8

9. How does it work?
- Copy on Write technique
 A space saving data backup technique that makes a
copy of the original data only if it’s modified.
Writes B to replace A
Copy
B
A A
Original Data (VD) Copy (Snapshot)
9

10. How does it work?
- Snapshots establishment
Timeline
10

11. How does it work?
- Snapshots establishment
Timeline
VD at 2PM
A B C D
11

12. How does it work?
- Snapshots establishment
Snapshot1 at
2:00 PM
Timeline
VD at 2PM
A B C D
12

13. How does it work?
- Snapshots establishment
No
Changes
Snapshot1 at
2:00 PM
Timeline
VD at 2PM
A B C D
13

14. How does it work?
- Snapshots establishment
No
Changes
Snapshot1 at
2:00 PM
No Changes
Timeline
VD at 2PM VD at 3PM
A B C D A B C D
14

15. How does it work?
- Snapshots establishment
No
Changes
Snapshot1 at Snapshot2 at
2:00 PM 3:00 PM
No Changes
Timeline
VD at 2PM VD at 3PM
A B C D A B C D
15

16. How does it work?
- Snapshots establishment
Replaces
No B with E
Changes Replaces
Snapshot1 at Snapshot2 at D with F
2:00 PM 3:00 PM
No Changes
Timeline
VD at 2PM VD at 3PM
A B C D A B C D
16

17. How does it work?
- Snapshots establishment
Replaces
No B with E
Changes Replaces
Snapshot1 at Snapshot2 at D with F
2:00 PM 3:00 PM
No Changes B D
Timeline
VD at 2PM VD at 3PM
A B C D A B C D A E C F
17

18. How does it work?
- Snapshots establishment
Replaces
No B with E
Changes Replaces
Snapshot1 at Snapshot2 at D with F Snapshot3 at
2:00 PM 3:00 PM 4:00 PM
No Changes B D
Timeline
VD at 2PM VD at 3PM
A B C D A B C D A E C F
18

19. How does it work?
- Snapshots establishment
Replaces Replaces
No B with E A with G
Changes Replaces Replaces
Snapshot1 at Snapshot2 at D with F Snapshot3 at C with H
2:00 PM 3:00 PM 4:00 PM
No Changes B D
Timeline
VD at 2PM VD at 3PM
A B C D A B C D A E C F
19

20. How does it work?
- Snapshots establishment
Replaces Replaces
No B with E A with G
Changes Replaces Replaces
Snapshot1 at Snapshot2 at D with F Snapshot3 at C with H
2:00 PM 3:00 PM 4:00 PM
No Changes B D A C
Timeline
VD at 2PM VD at 3PM
A B C D A B C D A E C F G E H F
20

21. How does it work?
- Snapshots establishment
Replaces Replaces
No B with E A with G
Changes Replaces Replaces
Snapshot1 at Snapshot2 at D with F Snapshot3 at C with HSnapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
No Changes B D A C
Timeline
VD at 2PM VD at 3PM
A B C D A B C D A E C F G E H F
21

22. How does it work?
- Snapshots establishment Futur
Replaces Replaces
No B with E A with G e
Changes Replaces Replaces chang
Snapshot1 at Snapshot2 at D with F Snapshot3 at C with HSnapshot4 at es
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM
A B C D A B C D A E C F G E H F
22

23. How does it work?
- Snapshots establishment Futur
Replaces Replaces
No B with E A with G e
Each snapshot records accumulated changes until next snapshot is takenchang
Changes Replaces Replaces
Snapshot1 at Snapshot2 at D with F Snapshot3 at C with HSnapshot4 at es
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F G E H F
23

24. Rollback Snapshots
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F G E H F
24

25. Rollback Snapshots
Rollback from
5PM to 4PM
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F G E H F
25

26. Rollback Snapshots
Rollback from
5PM to 4PM
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F A
G E C
H F
26

27. Rollback Snapshots
Rollback from
5PM to 4PM
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F A
G E C
H F
27

28. Rollback Snapshots
Rollback from
5PM to 3PM
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F A
G E C
H F
28

29. Rollback Snapshots
Rollback from
5PM to 3PM
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F A
G E B
C
H F D
29

30. Rollback Snapshots
Rollback from
5PM to 3PM
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F A
G E B
C
H F D
30

31. Rollback Snapshots
1. Restoring recorded changes in order
2. Only older snapshots are kept after rollback
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F A
G E B
C
H F D
31

32. Delete Snapshots
 Consider dependencies before deleting snapshots.
 Snapshots taken earlier will be deleted along with the
target snapshot.
32

33. Snapshots Dependencies
When delete snapshots…
Delete a snapshot involves deletion of earlier ones
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
Future
No Changes B D A C Changes
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F G E H F
33

34. Snapshots Dependencies
When rollback snapshots…
Depe Depe Dep
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM nds 3:00 PM nds 4:00 PM ends 5:00 PM
On On On
B D A C
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F G E H F
34

35. Snapshots Dependencies
When rollback snapshots…
Lack of snapshots in-between makes it impossible
to roll back to the target
Snapshot1 at Snapshot2 at Snapshot3 at Snapshot4 at
2:00 PM 3:00 PM 4:00 PM 5:00 PM
B D A C
Timeline
VD at 2PM VD at 3PM VD at 4PM VD at 5PM
A B C D A B C D A E C F G E H F
35

36. TrioNAS LX U600Q
 Outstanding Performance  Advanced Protection
o Hardware RAID o Snapshot
o SSD caching o Volume clone
o Qsan Unified OS o Battery Backup Module
o AntiVirus
 Integrated Backup Solution  Storage Efficiency
o Amazon S3 Cloud backup o Thin Provisioning, DeDup, Compression
o Remote Replication o UnifiedAUTH
36

37. AegisSAN LX P600Q (iSCSI)
 10GbE iSCSI-6G SAS High Availability Systems  Outstanding Performance
 Intel Xeon Dual core CPU, Intel® Ethernet  QiSOE (Qsan Hardware iSCSI
10GbE offload engine)
 Dual Active controllers, and full redundant  Up to 640K IOPS, up to 4,000
and hot-pluggable design MB/s throughput
 2x 10GbE + 2x 1GbE iSCSI ports per controller
 SBB form factor, 4U24/3U16/2U12/2U24
 Support RAID 0, 1, 0+1, 3, 5, 6, 10, 30, 50, 60,
JBOD, N-way mirror, online volume
expansion 37

38. AegisSAN LX F600Q (Fibre Channel)
 8GbE FC-6G SAS High Availability Systems  Outstanding Performance
 Intel Xeon Dual core CPU  Up to 650K IOPS, up to 5,000
 Dual Active controllers, and full redundant and MB/s throughput
hot-pluggable design
 4x 8G FC + 2x 1GbE iSCSI ports per controller
 SBB form factor, 4U24/3U16/2U12/2U24
 Support RAID 0, 1, 0+1, 3, 5, 6, 10, 30, 50, 60,
JBOD, N-way mirror, online volume expansion
38

39. QsanTechnology.com
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