ben_brooks
2 Bronze

How to tell which initiator has data on an RDF1+Mir symdev

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Hello all,

Is there a fast way to come up with the list of all initiators that have any data being replicated on RDF1+Mir devices?

I need to list all my hosts that have any data being replicated via SRDF. ECN members on an earlier question post have shown me a fast way to find the masking views to which all my RDF devices belong, which works great for all my RDF1+TDEV devices in masking views. However, one of my RDF groups is nothing but RDF1+Mir devices that are not part of a storage group, so there's no masking view to look up.

I've never run into Mirror devices before, but I assume they're just clones of regular devices and those regular devices are masked to hosts like usual. (Am I right?) Is there a fast way to make a list of initiators masked to the source devices that are cloned to the RDF1+Mir devices?

Thanks for your help!

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seancummins
3 Argentum

Re: How to tell which initiator has data on an RDF1+Mir symdev

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Hi Ben,

The "Mir" part of RDF+Mir means that they are traditionally provisioned (or "disk provisioned") instead of virtually provisioned. This basically means that there is no layer of abstraction between the SymDev/LUN and its underlying disks. Most devices on VMAX today are TDEVs, which means they are virtually provisioned from pools.

There could be a few possible reasons why those RDF+Mir devices aren't in a storage group:

  • Perhaps someone decommissioned them from a host, but forgot to remove the RDF relationships.
  • They could be mapped to FA ports without the ACLX bit set. Without ACLX, there is no masking on a particular FA port -- anything mapped to that FA port is visible to any host that is zoned to the port.
  • Those devices could be clone targets (basically what you were implying with your initial guess of what "+Mir" meant). While the "+Mir" thing doesn't mean that they are clone targets, they still could be clone targets   To see if they are participating in clone sessions, run a 'symdev show <SymDevID>' on the devices and look for a section about Clone relationships... check to see if the device is paired with another device in a clone session.

Hope that helps,

- Sean

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seancummins
3 Argentum

Re: How to tell which initiator has data on an RDF1+Mir symdev

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Hi Ben,

The "Mir" part of RDF+Mir means that they are traditionally provisioned (or "disk provisioned") instead of virtually provisioned. This basically means that there is no layer of abstraction between the SymDev/LUN and its underlying disks. Most devices on VMAX today are TDEVs, which means they are virtually provisioned from pools.

There could be a few possible reasons why those RDF+Mir devices aren't in a storage group:

  • Perhaps someone decommissioned them from a host, but forgot to remove the RDF relationships.
  • They could be mapped to FA ports without the ACLX bit set. Without ACLX, there is no masking on a particular FA port -- anything mapped to that FA port is visible to any host that is zoned to the port.
  • Those devices could be clone targets (basically what you were implying with your initial guess of what "+Mir" meant). While the "+Mir" thing doesn't mean that they are clone targets, they still could be clone targets   To see if they are participating in clone sessions, run a 'symdev show <SymDevID>' on the devices and look for a section about Clone relationships... check to see if the device is paired with another device in a clone session.

Hope that helps,

- Sean

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ben_brooks
2 Bronze

Re: How to tell which initiator has data on an RDF1+Mir symdev

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Sean, I apologize for forgetting to mark this question as answered a year ago. Thank you for your thorough explanation and suggestions.

It turns out that all of my RDF1+Mir devices are CKD and mapped to ports on FICON directors. I can't find information about FICON directors and the ACLX bit, but I assume ports on FICON directors must work the same way as FA ports without the ACLX bit, as you describe in your second suggestion: all initiators zoned to the port can see all devices mapped to the port, which is the reason the devices aren't in initiator groups.

This invalidates my original question about listing the initiators that are using RDF1+Mir devices. In my environment, no RDF1+Mir is masked to any initiator.

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