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2 Bronze

Re: MetaLUN

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Best is to delete the second metalun, recreate the component luns and concatenate the original metalun with the newly created component luns.

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Re: MetaLUN

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The question that needs to be answered here is not what all the combinations of MetaLUN expansion are, but what is zzRMC trying to do?

ie:  If there is a striped metaLUN with 3 components for example, and you just want to expand it with another 3 components to add additional capacity, then you create the 3 new components individually, and use the expand wizard on the original MetaLUN to add the 3 new components simultaneously.  FLARE will stripe the 3 new components together, then concatenate the new stripe with the existing stripe, resulting in a new larger (complex) meta.

I also believe you can manually create the new striped meta, then concatenate it with the first, but the first process above was the recommended process last I heard.

If there is something else zzRMC is trying to, we need more information to provide the correct answer.

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4 Beryllium

Re: MetaLUN

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Totally Agree with Richard Anderson.

Can I concatenate a MetaLUN with another MetaLUN?

However, zzRMC has mentioned what he want to do. From what I understand he meant to concat 2 metaLUNs which is not possible.

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Re: MetaLUN

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I guess I meant *why* does he want to concatenate a MetaLUN to another MetaLUN?  Is there some other reason other than just add new space to the first MetaLUN?  If it's not just a simple capacity increase, then there may be some other process we should recommend.

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3 Silver

Re: MetaLUN

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Adding meta to meta LUN will create performance issue.

My suggestion is to create fresh new LUN with required size and meta members configuration. Perform LUN migration from old meta LUN to newly configured metalun. LUN migration is online activity. This process will happen in storage array background. New device takes the identity from old meta LUN and the new storage space will be available in the server.

Regards,

Mahesh

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Re: MetaLUN

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MP_storage wrote:

Adding meta to meta LUN will create performance issue.

I'd make a correction here.  "Adding meta to meta LUN *can* create a performance issue"  It's entirely dependent on how the meta components are laid out.  Meta's can also improve performance if done correctly.

There is one very important basic rule to follow with Meta's to avoid most of the performance issues..

NEVER stripe on the same physical disks, only Concatenate when Meta components are sharing disks.  Creating a Meta where multiple striped components are sharing the same disks will cause head thrashing and higher response times.

The same rule applies at the host level as well..  Don't allow LVM (VxVM, ASM, etc) striping across multiple LUNs coming from the same RAID Group.

If you have components that are created on separate RAID Groups, then Stripe them.  This will improve overall performance of the LUN due to the larger number of disks supporting the meta compared with a single LUN in one RG.

ie: A 200GB striped Meta across 3 x 4+1R5 RAID Groups will perform better than a single 200GB LUN in a single 4+1R5 RAID Group.  A 200GB concatenated Meta in a single RAID Group will perform roughly the same as a 100GB normal LUN in the same RAID Group.

If you just need to increase capacity and want to use free space that is in the same RAID Group as the existing LUN, then concatenate.

Of course, if you have the luxury of free space elsewhere in the array where you can create a new larger LUN, a LUN Migration to the new larger LUN would be a good idea.

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2 Bronze

Re: MetaLUN

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Thank you all for your responses.

Been back East. Just returned.

Sorry I didn't respond sooner.

Richard A, I followed your recommendations.

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