Check spare capacity on disk driver

[Hasu]

have a question about the calculation of spare capacity on 2 3PAR 7400 devices:
+ On 2 devices 3PAR 7400 using the same 920GB SSD, with CPG and Raid1, Size set 2data  System 3PAR_01 includes
+On disk driver of system 3PAR_01, spare capacity is 106GB. On disk driver of 3PAR_02, spare capacity takes up to 284GB

+ The system 3PAR_01 includes 8  SSD drivers. System 3PAR_02 includes 6 SSD drivers
why is there difference a spare capacity  between 2 hard drives on 2 3PAR systems?

How to determine (calculate) spare capacity on 3PAR? 

[Hasu]

https://drive.google.com/open?id=1eqy-c54U-rgOCntpuG9HXXuwET6xpVtb 

https://drive.google.com/open?id=15jguJ-RhKBMTMPCcd9NHCQEwEBhpXDpN 

I can't upload screen shot.

So a share link ggdriver for spare capacity information 

[SUBHAJIT KHANBARMAN_1]

Can you please provide the below output from both systems to understand what is the Spare policy defined ?

showsys -param

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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[SUBHAJIT KHANBARMAN_1]

May be you check below information,

Spare rate
A key parameter in the spare policy is the spare rate. The spare rate is a target amount of space to set aside for sparing expressed relative to the number of disks of a given type in the system. A spare rate of 24, for example, sets target spare space equal to the size of one drive for every 24 drives in the array.
The spare rate is defined based on the hardware configuration in the array as follows:
• Spare rate = 40 if there are any magazines present in the array (e.g., 10,000)
• Spare rate = 24 for all others such as 7400/7400c, 7450/7450c, etc.

Sparing algorithms defined
The spare option is set for the entire array and applied to each disk type (SSD, FC, NL) in the following way.
• Default: Roughly 2.5 percent with minimums
Small configurations (e.g., 7000’s with less than 48 disks, 10000’s with less than 80 disks) have a spare space target equal to the size of two of the largest drives of the type being spared.
• Minimal: Roughly 2.5 percent without minimums
Minimal is the same as default except for small configurations. When the configuration is small, minimal will only set aside spare space equal to one of the largest drives (compared to two for default) of the type being sized.
• Maximal: One disk’s worth in every cage
Spare space is calculated as the space of the largest drive of the drive type being sized for each disk cage.
• Custom: Implemented manually by the administrator using the createspare, showspare, and removespare commands.

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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