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Parity Initialization Settings

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Parity Initialization Settings


I'm struggeling at the moment on finding the "best" possible settings for Smart Arry Controller (P816i-a in particular on HPE DL380 Gen10) configs regarding Parity Initalization.
I've been through Google and also the Smart Array's user and configuration manuals and I cannot quite get my head around this.

Here is the thing:
I want to configure multipe RAID 5 or RAID 50 arrays. The default, while creating these kind of arrays is "Background Initialization". The other available option is "Rapid Parity Initialization". The concept of both is quite clear.

The user manual states on pages 19 to 20:
"Rapid parity initialization [...] 
• It speeds up the parity initialization process.
• It ensures that parity volumes use backed-out writes for optimized random write performance."

So, I definitely want that! I can wait. No problem.

Now the other, much bigger "BUT" where I really got confused:
Further down on page 20, there is an explaniation about "Regenerative writes":
"Regenerative writes [...]
Logical drives can be created with background parity initialization so that they are available almost instantly.
It allows the logical drive to be accessible when degraded"

What does this mean? If I want better performance on random writes which I obviously will only get if I chose "Rapid Parity Initalization" or "RPI", my data would not be accessible anymore when the volume is degraded?
As I understand in that case, "degraded" means: one failed drive in a RAID 5 configuration for instance. If that cannot happen with a RAID 5 when it is initialized by choosing "RPI", that would be very ridiculous.

Or is it just me overthinking things?
Maybe the concept of both settings is not so clear to me after all? Any ideas?



Re: Parity Initialization Settings


 This is normal ,when there is any hardware change or hardware replacement happen and background initialization parity initialization. It is a back ground process done by the smart array controller and no further action required . It will rectify automatically..

It work as per design .


Sanjeev Goyal

I am a HPE Employee

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