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Best Practice - # of Disks in a FAST VP Pool
Hello -
We have a CX4-240 running FLARE 30. Our goal is to collapse existing traditional RG/LUNs and migrate to FAST VP Pool. The array has the following types of drives: 450 GB FC, 600GB FC, 600GB FC, 1TB SATAII.
FAST Cache is enabled on a couple of 100GB SSDs.
We currently have an existing pool with 8x 1TB drives, and 8x 600GB FC drives. We'd like to expand the pool by adding the rest of the drives in the array after migrating/collapsing the traditional RGs/LUNs.
What is the best practice when it comes to FAST VP pools? According the EMC documentation, a pool can include all disks in the array. This is the path we are leaning towards; 1 pool with all disks in the array. Is this something you folks see out there? Multiple pools?
Also, we will be enabling Snapview in the array as we will be configuring it for Commvault's Snapprotect. Do you see any issues with creating Reserved LUNs off of FAST VP Pool/s?
For the Vault drives, I am thinking of leaving those on traditional RG.
Thanks for you input in advance.
kelleg
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January 28th, 2013 14:00
First off, is your requirement ease of managing capacity or performance? If performance then stay with raid groups, there is always more overhead with Pools.
For best performance Reserve LUNs should stay in traditional raid groups and do not enable FAST cache for those.
Create Pools for different types of usage. Just like with raid groups, if you want the best performance you should not put a lot of different types of applications in the same pool. If you have heavy random Write apps, then create a R10 Pool. If you have Database apps, then you should probably have two types of pools - R10 for the LOGs and Temp (no FAST cache ) and R5 for the database (FAST cache good for this).
There's a lot of good information in the FAST VP White Paper (two attached). See page 32 in the Oct 2011 White page for Best Practice recommendations.
glen
2 Attachments
EMC FAST VP for Unified Storage Systems—A Detailed Review Sept 2011.pdf
White Paper EMC VNX Virtual Provisioning - Applied Technology OCt 2011.pdf
A_Shawky
28 Posts
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January 28th, 2013 21:00
Hello vlr2714,
When creating or expanding pools, the recommended pools sizes are multiples of five for RAID 5 and multiples of eight for RAID 6.
When using different capacity drives to create a pool, it is best to do this in stages. For example, if you have ten 600 GB drives and five 300 GB drives, first create the pool selecting only the ten 600 GB drives, and then expand the pool by adding the other five 300 GB drives.
General speaking, having multiple pools will give you more flexibility, as you can create a pool with RAID-5 configuration for performance LUNs and other pool with RAID-6 configuration for capacity LUNs, it depends on your needs/preferences.
For Replication, You cannot use pool LUNs as private LUNs (Clones Private LUN, MirrorView Write Intent Log LUN) for SnapView and MirrorView replication software.
RRR
2 Intern
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5.7K Posts
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January 29th, 2013 02:00
Consider not putting different FC disks in the same pool! If you have a pool consisting of 300GB 15k disks and you add 600GB 15k later or even 900GB 10k later, then you end up with a pool which sees all those disks as the same tier, since they’re all FC!!! The FAST feature that normally would equalize based on performance will nog leave large parts of the bigger disk unused since they perform equally good as the disks that are equally filled, leaving empty space on the bigger disks. If you want to use disks of different capacity, consider creating different pools.
dynamox
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January 29th, 2013 04:00
is this documented somewhere ?
AnkitMehta
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January 30th, 2013 07:00
Glen has already provided the 2 must read documents before configuring VP. Moreover, he has already updated that it depends what you are looking for capacity or performance?! The configuration and responses will vary according to that choice. Moreover, I wouldn't recommend to stress Vault Drives much by utilizing it to its full capacity, if performance is your aim!
I strongly suggest to read EMC CLARiiON Best Practices for Performance and Availability lates release with other 2 docs before making any changes!
I bet it will help you understand the concept in a deeper sense! 
(To me, it has!)
dynamox
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January 30th, 2013 20:00
i though we could not mix raid types in a pool on Clariion (flare 30), can we ?
JonK1
247 Posts
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February 6th, 2013 04:00
Correct, you can only mix in R32 which is not available for the CLARiiON, only the VNX.
dynamox
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February 6th, 2013 05:00
Oops..read it as mixing r5 and r6 in one pool .
A_Shawky
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February 6th, 2013 05:00
Hi dynamox,
That is correct mixed Pools are only available in R 32 so, only for VNX.
I mentioned 2 configurations of 2 pools, and did not mentioned that it is mixed in one pool
AnkitMehta
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February 7th, 2013 22:00
Was your question answered correctly? If so, please remember to mark your question Answered when you get the correct answer and award points to the person providing the answer.
Remembering to mark the question Answered helps others with similar problems and awarding points helps motivate people to take the time answer you questions.
- Ankit
RRR
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5.7K Posts
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February 14th, 2013 02:00
I know I saw it somewhere, but it is discussed here before: https://community.emc.com/message/657548#657548. When I see it in the documentation, I'll let you know.