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May 14th, 2012 06:00
Creating striped metas on VMAX with FAST VP
Hello community ,
I've been involved with VMAX since a few weeks now and I was wondering whether or not creating striped metas in a pool is good for performance or whether or not it's better to create concattenated metas?
In my DMX days I've learned that 3-way striping always should be avoided: 1) RAID5(3+1); 2) striped META; 3) host based striping. 2 Out of 3 is ok, but all 3 is not. So in the environment I'm working in right now I'm seeing all 3 implemented and I was wondering is this is ok. I'm reading through "Best Practices for Fast, Simple Capacity Allocation with EMC® Symmetrix® Virtual Provisioning™
Technical Notes
P/N 300-006-718
REV A13
June 8, 2011", but I'm not sure what it says. What's your professional oppinion about this ?
Quincy561
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May 14th, 2012 07:00
Yes, multiple levels of striping is not a good idea on traditionally provisioned volumes. This is because on thick volumes you want to keep LBA addresses close to one another on the disk to reduce seeks.
Since VP is already wide striped over all the disk, the additional striping doesn't really impact the performance the same way it would on a thick LUN.
The difference in performance from multiple Symm volumes active vs. 1 can be significant, which is why we recommend striped VP metas for performance.
RRR
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May 14th, 2012 07:00
Thanks Quincy56, this is what I wanted to hear! Is this your personal oppinion or an EMC certified answer ?
I also hear that SRDF can make a difference in what you should use: concat or striped. In weeks from now I'll have the ILT course I'll ask the instructor as well, but this question popped up this afternoon!
PS I thought you were an EMC employee.... or was this another Quincy?
Quincy561
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May 14th, 2012 07:00
Yes, I work in Symmetrix performance engineering, and this is a certified answer.
Look at the latest tech note you mentioned, it says something about striped metas being better for performance, but is somewhat vague about it.
Bottom line, if you don't need to expand them, or don't need to expand often, stripe the VP metas.
Quincy561
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May 14th, 2012 08:00
I'll be there!
RRR
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May 14th, 2012 08:00
see you in Vegas ?
RRR
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July 5th, 2012 04:00
Hmmmm, didn't see you
Sorry for the late response, but I'm catching up on old posts.
Were you tied to a booth or the vspex bus or what?