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how a thin striped meta is layed out on a thin pool
Hi
can some one expalain how a thin striped meta lun is laid out on a thin pool....
a diagram etc would be better.
Thanks
K
Unsolved
This post is more than 5 years old
50 Posts
0
2132
Hi
can some one expalain how a thin striped meta lun is laid out on a thin pool....
a diagram etc would be better.
Thanks
K
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Quincy561
1.3K Posts
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April 19th, 2012 04:00
Not really any different than a non-striped VP meta. The VP pool is allocated across TDATs 768k at a time in a round robin fashion for both concat and for striped.
A striped meta switches volumes every 960k.
The performance difference of striped vs concat metas on VP is not because of the backend but is because of the front end. The backend is already striped.
Kavan2
50 Posts
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April 19th, 2012 06:00
Quincy,
Thanks , when you say striped meta switches volume every 960k , by volume do u mean TDATs ???
Eg: TDAT 1 ->960k and then another TDAT2 960k etc. ??
I am still a bit confused.
Kavan
Quincy561
1.3K Posts
2
April 19th, 2012 06:00
The meta stripe is 960k. So a host writing sequentially to a striped meta will write to a different Symm device every 960k.
Let's assume we have an unallocated pool and never written TDEVs and a 4 member striped meta and 8 data devices in the pool and I write 6MB (8 VP extents worth) The TDAT pool is allocated in 768k chunks.
So in this example, the first 960k would allocate 2 VP extents on two TDATs, filling the first completely, and leaving 192k free in the second. Then the next meta member would do the same, and so on.
If the pool is pre-allocated, then none of this really matters.
I put a presentation together to illustrate this, but I can't attach it to the post.
Quincy561
1.3K Posts
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April 19th, 2012 06:00
Look in /incoming/Quincy56/Meta/
gozcom08
17 Posts
0
April 19th, 2012 06:00
Quincy56, any way you can place the presentation on the FTP site.
I'd like to get a copy.
Thanks
Sent from my iPhone
Kavan2
50 Posts
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April 19th, 2012 07:00
Sorry to be pain but what is the full address i:e ftp
Quincy561
1.3K Posts
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April 19th, 2012 08:00
ftp.emc.com
codyhosterman
286 Posts
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April 19th, 2012 16:00
There are several conditions in which the performance of concatenated thin metavolumes can be limited. Specifically:
There was an old recommendation of using concat metas because it used to not be possible to expand striped metas online therefore making concatenated more flexible.
Kavan2
50 Posts
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April 19th, 2012 16:00
Thanks Quincy, it has cleared my confusion.
From what I can see, Concat Thin meta and Striped Thin meta are both eventually striped on TDATs giving them more spindles, then why is Striped Thin Meta good for performance??
Also some of the post I read EMC recommends concat thin meta.
Quincy561
1.3K Posts
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April 19th, 2012 18:00
Concat metas are much easier to expand. If you don't need to expand, stripe.
Or if expansion is more important than performance concat.
Quincy561
1.3K Posts
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April 19th, 2012 18:00
There is limited concurrency for a single Symm volume with reads and writes to cache. More volumes active at once increases the available performance to and from cache.
moe2197
23 Posts
0
April 17th, 2013 14:00
Quincy56 - any chance you can put that presentation back on the ftp site?
Thanks!
Neel_c
32 Posts
0
August 14th, 2014 00:00
Quincy56
Having difficulty in understanding this. Can you please re-post the link to the presentation.
Quincy561
1.3K Posts
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August 14th, 2014 08:00
Quite an old thread resurrected.
I can't use the FTP site the way I did before. If you would PM me with your email I can send it, or provide some other place for me to upload it.
Neel_c
32 Posts
0
August 14th, 2014 08:00
Can you send the presentation to my personal email id
aalam.16@gmail.com
zigma6@gmail.com