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Allocation by FAST policy
This new feature within FAST was introduced with Enginuity level code 5876. I am interested in knowing why this feature is disabled by default?
From what I read the feature would benefit any environment from write failure.
Thanks in advance!
rawstorage
419 Posts
1
August 28th, 2013 04:00
J.B,
Our recommendation is certainly to turn this on in your environment, this is documented in the best practice guide available on support.emc.com
docu31003_FAST-VP-for-Symmetrix-VMAX-Theory-and-Best-Practices-for-Planning-and-Performance
As you have correctly stated it is generally a good thin, I guess at the moment the reason it's not default is that there are still previous versions of code out there that don't support it. Perhaps when 5875 goes EOSL and a few revisions have passed we will see this be the norm. It is not a replacement for monitoring your Pools but it will certainly give you an added protection, it will also ensure optimal placement of data if performance data already exist for the track groups so should cut down on some back end activity.
Fenglin1
2.1K Posts
1
August 27th, 2013 01:00
BTW, your question written to the users' own "Discussions" space don't get the same amount of attention and questions can go unanswered for a long time, You can select "Move" under ACTIONS along the upper-right. Then search for and select: "Symmetrix Support Forum" which would be the most relevant for this question.
Fenglin1
2.1K Posts
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August 27th, 2013 01:00
For your reference, this feature was also talked about in below ATE session.
https://community.emc.com/thread/177118
Fenglin1
2.1K Posts
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August 27th, 2013 01:00
Maybe the design assume the new allocation may not need demote or promote to different tier and just stay on the current tier which thin device is bound. I believe it's easy to enable the feature if anyone think it's useful.
J_B1
25 Posts
0
August 27th, 2013 10:00
Hi Fenglin Li,
Let me start off by thanking you for replying to this thread.
The benefit of the feature is unquestionable in my opinion because in the event that a thin pool fills up and the feature is not enabled, the writes will attempt to go to the pool that the devices are currently bound to and eventually fail until FAST demotes enough extents to a lower tier. Since this feature was recently introduced with 5876 I think what EMC is trying to do is, give its costumers a chance to do their research and assess if the feature makes sense for their environment as opposed to just rolling it out Enabled.
AranH1
2.2K Posts
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August 28th, 2013 09:00
The Allocate by Policy feature is not just for pool full conditions with the bound pool. Enginuity will attempt to allocate new writes from the appropriate pool in the policy with this enabled.
J_B1
25 Posts
1
August 28th, 2013 11:00
Thanks for your answer AranH!
J_B1
25 Posts
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August 28th, 2013 11:00
Paul,
Thank you for your answer and the link.