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6197
MetaLUN
My Array: NS-960
Flare 30
I know I can concatenate a LUN to a MetaLUN.
Can I concatenate a MetaLUN with another MetaLUN?
If so, how?
This post is more than 5 years old
29 Posts
0
6197
My Array: NS-960
Flare 30
I know I can concatenate a LUN to a MetaLUN.
Can I concatenate a MetaLUN with another MetaLUN?
If so, how?
Top
Storagesavvy
474 Posts
0
August 17th, 2012 12:00
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.
AnkitMehta
1.4K Posts
0
August 16th, 2012 13:00
The answer is NO
Refer the document attached for metaLUN Best Practices.
1 Attachment
metaLUN Detailed Review.pdf
zzRMC
29 Posts
0
August 16th, 2012 14:00
Hi Ankit,
Isn't a complex MetaLUN (page 29 - 30) a concatenation of two MetaLUN?
AnkitMehta
1.4K Posts
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August 16th, 2012 14:00
No.
My understanding and as per document:
A complex metaLUN consists of two or more metaLUN components.
metaLUN = Base LUN + Component LUN(s)
Complext metaLUN= 1st metaLUN + Component LUN of other metaLUN you want to concatenate.
My understanding is you asked, if this is possible:
Complex metaLUN = metaLUN 1(Base+ Comp) + metaLUN2 (Base+Comp), right?
bartdonders
25 Posts
1
August 17th, 2012 02:00
Best is to delete the second metalun, recreate the component luns and concatenate the original metalun with the newly created component luns.
AnkitMehta
1.4K Posts
0
August 17th, 2012 08:00
So which means No right?! You can't merge 2 metaLUNs via Expand Option as concat!
You can add a Comp. LUN of another metaLUN to other mLUN not whole metaLUN.
rupal1
433 Posts
1
August 17th, 2012 08:00
Vipin V.K, you are right. Component luns of a already created metalun cannot be detached and be used in another metalun. In all the figures wherever you see expansion the base lun is taken into account and the base lun has to be always taken whenever the meta is being done.
Reffer to page 31 of the doc thatAnkitM, mentioned.
Rule : MetaLUN can have one or more metaLUN components. At a minimum, the first component always includes the base lun.
Thanks
Rupal Rajwar
Vipin VK
812 Posts
0
August 17th, 2012 08:00
AnkitM, How can components LUN of a metaLUN be attached to another MetaLUN.
What I understood about complex meta is where we use both the expansion types,
1 MetaLUN + new components (either striped or concatenated)
Correct me if I am wrong.
AnkitMehta
1.4K Posts
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August 17th, 2012 08:00
True that, I am discussing this with a colleague and will post the response later this evening!
So far what I have read It is mLUN + new Comp. Lun but there are many types in this so I would need some time to post a detailed response!
AnkitMehta
1.4K Posts
0
August 17th, 2012 08:00
No.
Rupal Rajwar He can concat componenet LUN of other metaLUN after detaching it to the one he wants right?!
If yes, thats what I am trying to explain! :|
Vipin VK
812 Posts
0
August 17th, 2012 09:00
Once a metaLUN is destroyed, the components becomes normal LUNs. These LUNs can be added to an existing meta via concatenation.
Storagesavvy
474 Posts
1
August 17th, 2012 11:00
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.
AnkitMehta
1.4K Posts
0
August 17th, 2012 11:00
Totally Agree with Richard Anderson.
However, zzRMC has mentioned what he want to do. From what I understand he meant to concat 2 metaLUNs which is not possible.
MP_storage
47 Posts
0
August 17th, 2012 12:00
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
Storagesavvy
474 Posts
0
August 17th, 2012 12:00
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.