Hello all,

We are currently running an SVC cluster on 8.5.0.10 code and are planning to upgrade early in the new year to 8.7.0.x code. One thing that stands out to us are the changes to FlashCopy mappings/consistency groups in 8.7.0.x code.

Our current set up for FlashCopy is pretty simplistic, used specifically for just one application:

• A single consistency group is used
• 33 Flashcopy mappings are used in the one CG, simple 33 source volumes to 33 target volumes
• We use a Linux based script to run the relevant commands to lsfcconsistgrp, stopfcconsistgrp, and startfcconsistgrp, to re-flashcopy it daily for backup purposes. 
• We map the targets out to a backup host to mount, fsck, and back them up. 

We've had this working for about 8 years now. But with the introduction of 8.7.0.x we are reading in the manuals "Volume Group Snapshot replaces the FlashCopy function". 

Luckily we have a test environment with an SVC, which we have already upgraded  8.7.0.x already, but unfortunately it did not have any FC's prior to the upgrade. We've created them since via the CLI after the upgrade and hey presto the "Copy services" menu appears in the GUI for FC/FCCG management. We assume when we do it in our live environment the upgrade will leave all the FC/FCCG's as they are, and "Copy services" will stay in the new GUI. Is this correct?

Should we look to "convert" this FC/FCCG process to some sort of "Volume Group Snapshot" or another newer process after the upgrade? Needing the ability to map the targets on the same SVC cluster to another host is the key to the whole process of FC/FCCG. 

Also, another more generic question about new Volume Group Snapshots. Where are the snapshots held on the SVC, is it in memory, or within the volumes themselves, or somewhere else?

Thanks for your help,

Andy 

Hi Andrew,

We recommend switching to "volume group snapshots" due to safeguarded snapshots and pauseless snapshot feature. You can create snapshots, as well as thin clones of these snapshots, to map your hosts. These snapshots are held in the same pool and/or child pool. Your existing FlashCopy consistency groups will remain visible after upgrading to 8.7; however, 8.7 is the terminal release for the legacy FlashCopy consistency-group model. 

Read "Data Resiliency Designs: A Deep Dive into IBM Storage Safeguarded Snapshots" to learn about Safeguarded Snapshots and "Supercharge Your IBM Storage FlashSystem: Performance Tips and Tricks" Chapter 8 to learn benefits of pauseless snapshots. 

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Nezih Boyacioglu
IBM Community Hero
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