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Does this FAST config take effect for a volume?
Hello,
I have a VMAX volume FAST config policy question:
Below is the config detail:
MV1:
PG_1: 4 FA ports
CIG_1: hostA's all initiators
SG_1: normal SG without FAST and hostIO; has volume "AA" in it.
At same time, the volume "AA" is in a phantom storage group : SG_2. The SG_2 has a FAST policy.
The VMAX allows this config and I have configed it successful. The "AA" is provision to hostA and the I/O is ok.
My question is: Does the FAST policy take effect for the "AA" volume with this config?
Based on my understand, if the SG is not in a Masking View, it's only a "logic container" for the volumes in it, the FAST policy / hostIO properties for the SG will not take effect.
If I am wrong, please correct me.
Thanks
Liyu
KW160
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January 14th, 2015 07:00
I don't believe this is explicitly documented anywhere. I know it gets applied fairly regularly though. Please refer to the document:
"FAST VP for EMC® Symmetrix® VMAX® Theory and Best Practices for Planning and Performance Technical Notes
P/N 300-012-014" for the most up-to-date information.
KW160
121 Posts
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January 13th, 2015 20:00
To answer your question, "yes", the FAST VP policy will still take effect on the volume even though SG_2 is not part of a masking view. This is a well-documented use-case that can be employed when volumes from the same host require different FAST policies.
Host I/O controls are treated differently. The documentation states that you may not even apply an I/O limit if the SG is not part of a masking view. "Host I/O Limits can only be set for a storage group in a masking view."
Anonymous
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January 13th, 2015 21:00
Hi KW160,
Thanks a lot for so quick response! It's really helpful.
Do you know where can I get the article that has this use-case documented? With the docs of VMAX FAST, I can't find this usage.
Thanks
Liyu
Anonymous
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January 14th, 2015 16:00
Thank you very much!