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FlashSystem Partnership and Relationship Issues

By Shawn Bodily posted 14 hours ago

  

I’ve installed dozens of IBM FlashSystem storage units throughout the years and replication on about a third of them primarily for migration. But I recently had a different and challenging experience.

When attempting to create a partnership between a FlashSystem FS5200 with code level (8.4.2.1) and a FlashSystem FS5300 with code level (8.7.0.2), though we zoned them correctly via their REAL WWPNs, the GUI reported nothing was found on the fiber. Upon further review,  we discovered that the  system “layer” setting differed on the two units via the lssystem command as shown below:

IBM_FlashSystem:P9FS5200:superuser>lssystem |grep layer

layer storage

IBM_FlashSystem:P10FS5300:superuser>lssystem |grep layer

layer replication

 This is because the default system layer changed to replication in 8.6.3. In order to establish a proper relationship the system layer setting MUST match.

More information on system layers can be found at: https://www.ibm.com/docs/en/flashsystem-c200/9.1.0?topic=system-layers

When attempting to change the original FS5200 to replication, which is the recommendation as opposed to changing the FS5300 to storage, to match the FS5300, another error was encountered about other system/cluster nodes were detected.

This is because the zoning in place, does allow them to “see” other but not effectively talk to each other. So the resolution for this is to stop the communication between them. This can be done by removing the zone, disabling the port(s) the new storage unit is attached to, or physically unplugging the cables designated for the replication. In our case, we removed the zone. Then run the command below to change the layer on the FS5200 to match the new FS5300 (and is the recommendation) and then zone it back.

Disabled the zone.

Executed: chsystem -layer replication

Enable the zone.

This inturn allowed us to create the partnership successfully.

However the fun didn't stop there. While attempting to setup a replicated relationship we got the following error message:

CMMVC7176E The remote copy relationship could not be added to the consistency group because the cycling modes do not match.

However we initially didn't know we got the error. Because in the the GUI, when the task executed it just gave us the OK and went back to the previous screen there was no relationship showing in the list. So this was very confusing. So we did it again, this time make sure we chose to expand the "View Details" on the GUI screen executing the task, and that is what showed the error message.

Turns out this is because the new FS5300 does not have remote copy compatibility mode enabled.

To enable it as required, execute:

chcompatibilitymode -enable -feature remote_copy

This can be checked/validate via the lscompatibilitymode command as shown below:

IBM_FlashSystem:P10FS5300:superuser>lscompatibilitymode

feature            enabled in_use

remote_copy        yes     yes

multiple_io_groups no      no

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