Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Upon completion of this module, you should be able to: Describe SnapView Snapshot.

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Upon completion of this module, you should be able to: Describe SnapView Snapshot operations Configure and Manage SnapView Snapshots SnapView Snapshot1

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshots During this lesson the following topics are covered: Purpose of SnapView Snapshot SnapView Snapshots requirements SnapView Snapshots managed objects SnapView Snapshots theory of operations Lesson 1: Theory and Operation SnapView Snapshot2

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot3

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshots Requirements EnvironmentSystem Requirements HardwareVNX 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 SoftwareVNX Operating Environment for Block SnapView enabler Management SoftwareUnisphere UI Navisphere Secure CLI Admsnap Operating SystemsHP-UX IBM AIX Linux Solaris Windows Server Refer to EMC Support Matrix for a complete list SnapView Snapshot4

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot5

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot6

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot7

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot8

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot9

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot10

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot11

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation SnapView Snapshot12 8AM9AM Production Server A B C Source LUN Chunks A B C Chunks Session 9AM LUN 6LUN 7 LUN 8LUN 9 Reserved LUN Pool Source LUN Continuous I/O 1 Session 9AM is started Reserved LUN 6 is allocated COFW is enabled 1 1

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation (continued) SnapView Snapshot13 10AM A B C Source LUN Chunks Session 9AM LUN 6LUN 7 LUN 8LUN 9 Reserved LUN Pool A B C Chunks Snapshot of Source LUN 2 Snapshot of Source LUN is created but not activated 2 Server B Snapshot of Source LUN is added to the Storage Group of Server B 3 3 Not Ready Production Server R / W

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation (continued) SnapView Snapshot14 A B C Source LUN Chunks LUN 6LUN 7 LUN 8LUN 9 Reserved LUN Pool 4 Snapshot of Source LUN is activated 4 Snapshot of Source LUN A B C Chunks Session 9AM Session 9AM is allocated by Snapshot of Source LUN Server B Production Server 11AM R / W Virtual Source LUN (Snapshot of Source LUN) is made available (R / W) to Server B A B C Chunks

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation (continued) SnapView Snapshot15 A B C Source LUN Chunks LUN 6LUN 7 LUN 8LUN 9 Reserved LUN Pool 5 Production Server requests a change on Chunk “C” (COFW) 5 Snapshot of Source LUN A B C Chunks Session 9AM Server B Production Server 12PM R / W C’ 6 C 6 Original Chunk “C” is copied to the Reserved LUN 6 allocated by Session 9AM

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation (continued) SnapView Snapshot16 A B C’ Source LUN Chunks LUN 6LUN 7 LUN 8LUN 9 Reserved LUN Pool 7 Session 9AM pointer uses the original Chunk ‘C” from Reserved LUN 6 Snapshot of Source LUN A B C Chunks Session 9AM Server B Production Server 12PM R / W 7 C

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation (continued) SnapView Snapshot17 A B C’ Source LUN Chunks LUN 6 LUN 7 LUN 8LUN 9 Reserved LUN Pool 8 Snapshot of Source LUN A B C Chunks Session 9AM Server B Production Server 1PM R / W 8 C B’ Server B requests a change on Chunk “B” (COFW) B 9 9 Original Chunk “B” is copied to the Reserved LUN 6 allocated by Session 9AM and then modified by the write B’ ’

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Theory of Operation (continued) SnapView Snapshot18 A B C’ Source LUN Chunks LUN 6 LUN 7 LUN 8LUN 9 Reserved LUN Pool Snapshot of Source LUN A B’ C Chunks Server B Production Server 1PM R / W CB’ Session 9AM Session 9AM pointer uses Chunk B’ from Reserved LUN 6 0 1 0 1 B

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshots During this lesson the following topics were covered: Purpose of SnapView Snapshot SnapView Snapshots requirements SnapView Snapshots managed objects SnapView Snapshots theory of operations Lesson 1: Summary SnapView Snapshot19

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 Lesson 2: Configuring and Managing SnapView Snapshots SnapView Snapshot20

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshots 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 Lesson 2: Summary 32SnapView Snapshot

Copyright © 2014 EMC Corporation. All Rights Reserved. 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 SnapView Snapshot33

Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Upon completion of this module, you should be able to: Describe SnapView Snapshot.

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Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Upon completion of this module, you should be able to: Describe SnapView Snapshot.

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Presentation on theme: "Copyright © 2014 EMC Corporation. All Rights Reserved. SnapView Snapshot Upon completion of this module, you should be able to: Describe SnapView Snapshot."— Presentation transcript:

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