can some one expalain how a thin striped meta lun is laid out on a thin pool....
a diagram etc would be better.
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.
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.
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.
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.
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.