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LSI MegaRAID virtual drive initialization

raid ssd performance initialization

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#1 lunadesign

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Posted 12 July 2014 - 06:55 PM

Can someone please confirm what it means to "initialize" a virtual drive on an LSI MegaRAID card?

I've read in some places that it's writing zeroes to all the drives (Fast Init only does it to the first/last 10 MB, Slow and Background Init do the entire drive space).

Assuming I'm correct, if I'm setting up a RAID 1 or RAID 10 with SSDs that I've just secure erased, wouldn't writing zeroes to the drives (A) be total overkill since the drives are already consistent and ( B) severely impact performance until GC has time to clean things up?

I've also heard that performance may be degraded if the RAID card isn't sure the drives are consistent.  Is this true?  If so, would running a consistency check shortly after setting up the virtual drive solve that?

 

Many thanks in advance!


#2 continuum

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Posted 16 July 2014 - 08:43 PM

at performance may be degraded if the RAID card isn't sure the drives are consistent.  Is this true?  If so, would running a consistency check shortly after setting up the virtual drive solve that?
Yes and yes, but that would largely be the same thing as initializing the whole RAID to start with in this case.

 

The controller has no way to verify the drives are consistent pre-initialization.


#3 lunadesign

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Posted 16 July 2014 - 09:27 PM

Yes and yes, but that would largely be the same thing as initializing the whole RAID to start with in this case.

 

The controller has no way to verify the drives are consistent pre-initialization.

 

Is it truly the same thing?  My understanding was that the consistency check is all reads except when it finds non-matching sectors when it writes to make the sectors match.  But if the drives were truly wiped, they should fully match.  In contrast, I understand that initialization is writing zeroes regardless of what's already on the drive.






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