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February 14th, 2021 16:00

Powermax and Storage Group restrictions, limitations... seeking some discussion

New to Powermax but familiar with Arrays.  I'm stumbling with Storage Groups (SGs) and encountering  restrictions - thus seeking other opinions/direction or best practices. EMC professional services got us started with the below standard and we are continuing . Here is an example of a restriction and ask for your opinion…

SG_ParentA-(SPR: None) .. SG_ChildA-(SPR: 01) ..... disk_1, disk_2, disk_3          (masked to … HOST_A)

SG_ParentB-(SPR: None) .. SG_ChildB-(SPR: 01) ..... disk_1, disk_2                        (masked to … HOST_B)

Suddenly we have a requirement to have disk_3 visible to both Host_A and Host_B. We cannot add the device to both SG’s without error: device cannot belong to more than 1 SG in use by FAST….

I’ve even tested with Parent-child SG’s but just Storage Groups….

SG_A-(SPR: 01) ..... disk_1, disk_2, disk_3     (masked to … HOST_A)

SG_B-(SPR: 01) ..... disk_1, disk_2                   (masked to … HOST_B)

Fails again when trying to add disk_3 to SG_B (and coexist in SG_A)….

Any suggestions… is this normal…. What have we gotten ourselves into? Please understand that its up to the hosts not to corrupt the volumes, etc… but this is a normal practice in clustering software or in SOLARIS….

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February 15th, 2021 11:00

Hi,

I believe it is a limitation of storage using a FAST policy.  

March 25th, 2021 19:00

Yes yes... this seems to be correct.... So in other Enterprise Storage solutions (such as DELL-EMC:VIPRC, IBM, HDS, etc)... the ability  to take an existing provisioned volume and then when required - provision to another host is supported.  And easy.

The only way is to remove service-level-object and system-resource-pool

symsg -sid 207 -sg sean set -noslo -nosrp

Of course ... 2 hosts with access to the same volume (without clustering software) is now at the ownership of the Server Administrator.....but this is not a rare thing.  I do it for life-cycling , migrations and even to resolve a problem .. and the lists goes on.   

Please do not respond that SSD's are fast and there shouldn't be a problem removing a SG's storage 'performance tier'.  We have customers that pay accordingly for Diamond / Silver / Bronze.... and the powermax was built to do this (although all the disk are exactly the same)...... 

 

But hey hey ...  that's where we are...

 

 

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