But then the array needs to keep track of where data is so that it knows what is "good" and what is "bad." Instead it takes the array to a known good state to start out with and you don't have to start out with blank disks. -----Original Message----- From: linux-raid-owner@xxxxxxxxxxxxxxx [mailto:linux-raid-owner@xxxxxxxxxxxxxxx] On Behalf Of Jan Engelhardt Sent: Monday, April 30, 2007 1:35 PM To: Dan Williams Cc: linux-raid@xxxxxxxxxxxxxxx Subject: Re: RAID rebuild on Create On Apr 30 2007 11:19, Dan Williams wrote: >> >> when a user does `mdadm -C /dev/md0 -l <any> -n <whatever fits> >> <devices>`, the array gets rebuilt for at least RAID1 and RAID5, even if >> the disk contents are most likely not of importance (otherwise we would >> not be creating a raid array right now). Could not this needless resync >> be skipped - what do you think? > > If you want his behavior you can always create the array with a > 'missing' device to hold off the resync process. Otherwise, if all > disks are available, why not let the array make forward progress to a > protected state? Having a device missing in the array does not create a protected state as you call it. What I was out at - can't the array wait with syncing blocks until I have actually written something there for the first time? This should not impact protection. _Especially_ if one starts out with blank disks. Then the resync process copies zeroes to zeroes (before we even run mkfs). And it chews a bit on PCI bandwidth. > Also, the resync thread automatically yields to new data coming into > the array, so you can effectively sync an array by writing to all the > blocks. Jan -- - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
