3PAR 8200 CPG Set Size

[Strieckel]

Hi Folks,

I hope you are able pointing me into the right direction?

We have a 3PAR 8200 attached with 10 x 1,92TB SSDs.
Current CPG Set size is 4+1 Raid 5.

I need to add now 8 x 1.92TB SSDs more to the Storage getting in total 18 SSDs installed.

Are you able to let me know which Set Size would fit best running with 18 SSDs?

I believe 5+1 is that true?

Or do I have to think Node wide means 8+1 as each Node owns 8 SSDs, which would worse than?

Many thanks for your help.

Br
Joerg

[SUBHAJIT KHANBARMAN_1]

You can check the best practice gudie,

https://h20195.www2.hpe.com/v2/GetPDF.aspx/4AA4-4524ENW.pdf

"Solid-state drive CPGs
Consider the following best practices when creating SSD CPGs:
• SSD CPGs should be configured with RAID 6 with the default set size. This will yield a superior performance/capacity ratio and 6+2 on systems that have enough SSDs to support 6+2, for larger systems R6 14+2 gives the best capacity / performance mix.
• The growth increment should be set to the minimum value, which is 8 GB per node pair.
– On two-node systems, set the value to 8 GB.
– On four-node systems, set the value to 16 GB.
– On six-node systems, set the value to 24 GB.
– On eight-node systems, set the value to 32 GB.
To set the CPG growth increment to a lower value than the default, check the Show advanced option box.
• Availability should be left to “cage level” (the default option) if the system’s configuration allows for it. If not, it should be set to “magazine level” availability. You can change this by checking the Advanced options box in the SSMC. "

Hope this helps!
Regards
Subhajit

I am an HPE employee

If you feel this was helpful please click the KUDOS! thumb below!

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[Strieckel]

Hi Subhajit,

many thanks for your output, but this is not the answer I am looking for.

The Storage is used for Development and Testing and not real in production, so we want to go further with RAID 5 getting a higher capacity.

But I am unsure which Set size under Raid 5 fit best when 18 Disks are installed?

Should I go with a Set size = 5+1?

Would this fit best for 18 Disks installed as this dividable? 18 / 6 (5+1) = 3

Or should I calculate the Set size from node perspective as each Node own the half of disk installed? 18 / 2 = 9 = set size 8+1

Br
Joerg

[SUBHAJIT KHANBARMAN_1]

As you have mentioned you look for capacity then you can go for set size 9 (8+1) because that will help you less number of drive will go for parity

Keep in mind that bigger the set size it will increase Write latency because parity calculation will take time.

Hope this helps!
Regards
Subhajit

I am an HPE employee

If you feel this was helpful please click the KUDOS! thumb below!

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