Transcript R_MOD_11-SnapView_Snapshot

SnapView Snapshot
Upon completion of this module, you should be able to:
• Describe SnapView Snapshot operations
• Configure and Manage SnapView Snapshots
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
1
SnapView Snapshots
Lesson 1: Theory and Operation
During this lesson the following topics are covered:
• Purpose of SnapView Snapshot
• SnapView Snapshots requirements
• SnapView Snapshots managed objects
• SnapView Snapshots theory of operations
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
2
SnapView Snapshots
• SnapView Snapshot - an instantaneous frozen virtual copy of a
LUN on a storage system
 Allows a secondary server to view a point-in-time copy of a source
LUN
 Snapshots are created instantly – no data is copied at creation time
 Snapshot will not change UNLESS the user writes to it
 Original view available by deactivating changed Snapshot
• Virtual LUN
 Not a real LUN - made up of pointers, original and saved blocks
 Uses a copy on first write (COFW) mechanism
 Requires a ‘save area’ – the Reserved LUN Pool
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
3
SnapView Snapshots Requirements
Environment
System Requirements
Hardware
VNX Storage System
Two or more Servers (if the SnapView
snapshot is to be accessed by a host), each
attached to the VNX that will run SnapView
Storage System Software
VNX Operating Environment for Block
SnapView enabler
Management Software
Unisphere UI
Navisphere Secure CLI
Admsnap
Operating Systems
HP-UX
IBM AIX
Linux
Solaris
Windows Server
Refer to EMC Support Matrix for a complete
list
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
4
SnapView Snapshots Managed Objects
• Source LUN
 The LUN containing production data
• SnapView Session
 Process of defining the point-in-time designation
 Invokes COFW activity for updates to the source LUN
• Reserved LUN
 Supports the pointer-based design of SnapView Snapshot
 Used to save data chunks
• SnapView Snapshot
 The defined virtual LUN
 Presented to the secondary host
 Enables visibility into running sessions
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
5
SnapView Session
• SnapView Session
 COFW mechanism starts and ends with session
 SnapView snapshot appears off-line until there is an active session
 A multiple Source LUN session can be started consistently
• SnapView Session name
 Sessions should have significant names
 Compatibility with admsnap – use alphanumerics, underscores
 It’s case-sensitive!
• Session consistent start
 Holds I/O until session starts on all source LUNs
 Fails if any source LUN fails
 Does not allow other LUNs to be added to session
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
6
Copy on First Write
• Allows efficient utilization of copy space
 Uses a dedicated save area – the Reserved LUN Pool
 Total capacity of Reserved LUN Pool LUNs is approximately 20% of
total source LUN sizes
• Saves original data chunks – once only
 Chunks are a fixed size - 64 KB (128 blocks)
 Chunks are saved when they’re modified for the first time
• Allows consistent ‘point-in-time’ views of LUN(s)
• Allows rollback to previous points in time
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
7
Reserved LUN Recommendations
• Total number of Reserved LUNs is VNX model-dependent
• Reserved LUNs may be of different sizes
• No checking of size, disk type or RAID type when allocated
• Use SAS drives with write-cache enabled LUNs
• Thin LUNS cannot be used in the RLP
• Create 2 RLs per Source LUN, each 10% of Source LUN size
• Example
 LUNs to be snapped: 10 GB, 20 GB, 30 GB, 100 GB
 Average LUN size = 160 GB/4 = 40 GB
 Make each Reserved LUN 4 GB in size
 Make 8 Reserved LUNs
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
8
SnapView: Stopping Sessions
• Sessions may be manually stopped by the user
• SnapView Sessions are automatically stopped
 If the Reserved LUN Pool fills (attempt to use too much disk space)
• Stopping the SnapView Session
 Removes all memory map entries associated with session
 Reserved LUN Pool space is made available for reuse
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
9
Host I/O to a Source LUN
• Three possible types of I/O to a source LUN
1. Read or write request with no active session
 I/O passed to driver below in I/O stack
2. Read request with active session
 I/O passed to driver below in I/O stack
3. Write request with an active session
 If the original data is not already in the Reserved LUN Pool, Copy on
First Write is performed
 Original data read from source LUN
 SnapView finds an unused area in the Reserved LUN Pool
 Original data written to unused area in Reserved LUN Pool
 Entry made in memory and on disk to indicate where original data is
written
 Write request passed to driver below in I/O stack
 If the original data is already in the Reserved LUN Pool, the write
request is passed to driver below in I/O stack
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
10
Host I/O to a Snapshot
• Three possible types of I/O to a Snapshot
1. Read or write request with no active session is intercepted by
the SnapView driver
 I/O requests fail – drive appears off-line
2. Read request with an active session
 Memory map consulted to determine if the data should be read
from the Reserved LUN Pool or from the source LUN
3. Write request with an active session
 Write requests are allowed; however, any data written to a
Snapshot is not persistent beyond the end of the session
 The memory map is consulted to determine if the original data has
been written to the Reserved LUN Pool (i.e., COFW has already
occurred)
 If not, a new map entry is created, and the original data is written
to the RLP. The new data is written to the Source LUN
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
11
SnapView Snapshot Theory of Operation
Production
Server
Reserved LUN Pool
Source
LUN
1
Chunks
A B C
LUN 6
LUN 7
LUN 8
LUN 9
Continuous
I/O
1
Chunks
A B C
Session 9AM
1 Session 9AM is started
Reserved LUN 6 is allocated
Source
LUN
8AM
Copyright © 2014 EMC Corporation. All Rights Reserved.
COFW is enabled
9AM
SnapView Snapshot
12
SnapView Snapshot Theory of Operation
(continued)
Production
Server
R/W
Reserved LUN Pool
Source LUN
Chunks
A B C
Session 9AM
2
A B C
LUN 6
LUN 7
LUN 8
LUN 9
2 Snapshot of Source LUN is created
but not activated
Server B
3 Snapshot of Source LUN is added
to the Storage Group of Server B
Chunks
Not Ready
Snapshot of
Source LUN
3
10AM
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
13
SnapView Snapshot Theory of Operation
(continued)
Production
Server
R/W
Reserved LUN Pool
Source LUN
Chunks
A B C
Session 9AM
4
4
A B C
LUN 6
LUN 7
LUN 8
LUN 9
Snapshot of Source LUN is activated
Session 9AM is allocated by Snapshot
of Source LUN
Server B
Virtual Source LUN (Snapshot of Source LUN)
is made available (R / W) to Server B
Chunks
R/W
Snapshot of
Source LUN
11AM
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
14
SnapView Snapshot Theory of Operation
(continued)
Production
Server
Reserved LUN Pool
Source LUN
C’
R/W
5
Chunks
A B C
C
6
Session 9AM
A B C
LUN 6
LUN 7
LUN 8
LUN 9
5
Production Server requests a change
on Chunk “C” (COFW)
6
Original Chunk “C” is copied to the
Reserved LUN 6 allocated by Session 9AM
Server B
Chunks
R/W
Snapshot of
Source LUN
12PM
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
15
SnapView Snapshot Theory of Operation
(continued)
Production
Server
R/W
Reserved LUN Pool
Source LUN
Chunks
C
A B C’
7
Session 9AM
7
LUN 6
LUN 7
LUN 8
LUN 9
Session 9AM pointer uses the original
Chunk ‘C” from Reserved LUN 6
Server B
A B C
Chunks
R/W
Snapshot of
Source LUN
12PM
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
16
SnapView Snapshot Theory of Operation
(continued)
Production
Server
Reserved LUN Pool
Source LUN
9
R/W
Chunks
B B’C
A B C’
Session 9AM
A B’ C
LUN 6
LUN 7
LUN 8
LUN 9
8
Server B requests a change on Chunk
“B” (COFW)
9
Original Chunk “B” is copied to the
Reserved LUN 6 allocated by Session 9AM
and then modified by the write
Chunks
R/W
Server B
B’
8
Snapshot of
Source LUN
1PM
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
17
SnapView Snapshot Theory of Operation
(continued)
Production
Server
R/W
Reserved LUN Pool
Source LUN
Chunks
B B’ C
A B C’
LUN 6
LUN 7
10
LUN 8
Session 9AM
10
LUN 9
Session 9AM pointer uses
Chunk B’ from Reserved LUN 6
Server B
A B’ C
Chunks
R/W
Snapshot of
Source LUN
1PM
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
18
SnapView Snapshots
Lesson 1: Summary
During this lesson the following topics were covered:
• Purpose of SnapView Snapshot
• SnapView Snapshots requirements
• SnapView Snapshots managed objects
• SnapView Snapshots theory of operations
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
19
SnapView Snapshots
Lesson 2: Configuring and Managing SnapView Snapshots
During this lesson the following topics are covered:
• Managing the Reserved LUN Pool
• Managing SnapView sessions and SnapView snapshots
• Configuring and managing SnapView sessions and SnapView
snapshots with the Wizards
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
20
Reserved LUN Pool Management
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
21
Reserved LUN Pool LUNs – Free LUNs
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
22
Reserved LUN Pool – Allocated LUNs
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
23
Monitoring Reserved LUN Pool Usage
Storage System > System > Monitoring and Alerts > SP Event Logs
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
24
SnapView Sessions
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
25
SnapView Session Properties
Storage System > Data Protection > Snapshots > LUN Snapshots
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
26
SnapView Session – Start / Stop
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
27
SnapView Snapshot
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
28
Snapshot Session Rollback
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
29
Snapshot Session Rollback Properties
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
30
Snapshot Configuration Wizard
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
31
SnapView Snapshots
Lesson 2: Summary
During this lesson the following topics were covered:
• Managing SnapView snapshots and SnapView sessions
• Configuring and managing SnapView snapshots and sessions
with the Snapshot Wizard
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
32
Summary
Key points covered in this module:
• SnapView Snapshot is an instantaneous frozen virtual copy of a
LUN on a VNX storage system
• SnapView Snapshot uses COFW technology
• Snapshot Wizard can be used to Configuring and managing
SnapView snapshots and sessions
Copyright © 2014 EMC Corporation. All Rights Reserved.
SnapView Snapshot
33