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May 9th, 2024 15:27
ME5024 One Pool or Two
Hello,
I am setting up a ME5024 with 10x 4TB disks for VM storage and was wondering about pool setup. If I use the auto setup it creates one RAID 6 30TB pool if I create a manual pool of 2x RAID 6 and one RAID 1 using both controllers I would lose about 11TB of space. How much of a performance hit would I take if I create only one pool on one controller?
Thanks,
Riverstech
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DELL-Chris H
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May 9th, 2024 20:15
Riverstech,
What that is saying is the data stripes in a raidset would be a power of 2 for best performance. So with 10 disks then a raid 6 stripe would use 2 for parity and 8 for data (which is a power of two). Now if we instead break this up into two disk groups in seperate pools to have a pool A on controller A and pool B on controller B we will lose the power of 2 but have the benefit of utilizing the frontend ports of both controllers simultaneously when doing IO to both pools however in my personal opinion people usually max out the throughput of the drives well before maxing out the throughput of the host ports, so I would lean towards one pool on controller A and controller B will still work for failover or ALUA when needed.
You can find more about it here.
Let me know if this helps.
riverstech
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May 10th, 2024 14:13
@DELL-Chris H I agree one pool sounds like the way to go Thanks!
The_LostIT_Guy
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May 23rd, 2024 18:23
DELL-Charles R
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May 23rd, 2024 20:36
Hello,
I would agree and say yes as the documentation he provided is the Dell PowerVault ME4 Series Storage System Administrator’s Guide
https://dell.to/4ajmSSe
The_LostIT_Guy
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June 13th, 2024 17:21
@DELL-Chris H @DELL-Charles R I'm back...I realized that I didn't ask why Chris made this recommendation.
I understand that most people will max out the perf of their drives before the host ports . . . What is your reasoning for this exactly? Do clear benefits of running 1 pool vs 2 exist?
(edited)
DELL-Chris H
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June 13th, 2024 19:03
The decision of whether to use a single point of failure or not depends on various factors such as expected performance and safety. There is no definitive answer as it involves weighing all the pros and cons. However, when it comes to newer storage systems with low counts of drives, it is generally easier to overdrive the disks before the storage ports. This means that the controllers can process and send data faster than the disks can spin and process.
To provide an analogy, imagine having two workers assigned to the same task. In this scenario, it is generally better to utilize both workers, allowing them to share the workload, rather than having one worker do all the work while the other simply watches.
However, it is crucial to consider the potential drawbacks and risks associated with this approach. Relying heavily on a single worker or overdriving the disks can create a single point of failure, and if that worker becomes unavailable or the disks fail, it could lead to performance issues or data loss.
Therefore, it is necessary to carefully evaluate the expected performance and safety implications of both scenarios and make an informed decision based on the specific requirements and constraints of the system in question.
Hope this helps.