Re: RAID 5 build time optimization question and experiments.

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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