Re: RAID 5 build time optimization question and experiments.

[Joe Landman <landman@scalableinformatics.com>]

Gsacapital!

Robin Hill wrote:
> On Fri Dec 11, 2009 at 02:55:31PM +0000, Cat'Killer wrote:
> 
>> I found a way using Doug Gilbert's great sg3utils to zero all these
>> disks in a very efficient manner, using sgp_dd, at near drive
>> bandwidth, and proceeded to zero all the disks fully in about 4 hours!
>>
>> Once done, I then created a RAID 5 on 10 disks, waited for the rebuild
>> to complete, stopped the array using mdadm, and dumped each of the
>> RAID's components superblocks to files.
>>
> <-snip->
>> The create worked fine and I waited for the rebuild to be complete
>> before stopping the array and dumping the SBs.
>>
>> I then proceeded to write these same superblocks to 10 new similar
>> disks in a different system.
>>
> You could just do the create with --assume-clean, which should take very
> little time at all.  If the drives were zeroed initially then this will
> give you valid parity data.
> 
> Cheers,
>     Robin
> 


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