On Sat, 2009-05-30 at 20:55 +0200, Goswin von Brederlow wrote: > Redeeman <redeeman@xxxxxxxxxxx> writes: > > > On Sat, 2009-05-30 at 14:35 +0100, John Robinson wrote: > >> On 30/05/2009 06:44, SandeepKsinha wrote: > >> > Hi all, > >> > > >> > Say If I have a RAID 5 array of 50GB of five disks of 10GB each. > >> > > >> > I have data of 5GB. When a disk fails and replaced with a spare disk. > >> > Will the reconstruction happen only for the 5GB allocated disk blocks > >> > or it will happen for the whole disk size. > >> > >> The whole disc size, for now anyway; md does not currently note which > >> blocks have been used by its client (the filesystem, LVM, whatever). > >> > >> > Is it possible to make reconstruction intelligent enough to keep it optimized ? > >> > >> This has been discussed in combination with supporting SSD drives' TRIM > >> function, and would mean md had to keep track of used chunks or possibly > >> even sectors using a bitmap or something like that, but whether anyone's > >> working on it I don't know. > > > > I would say it should be possible to 'query' the filesystem for that > > information. Obviously this will only work if you run a filesystem on it > > which supports it, but it would seem like a nicer solution than a bitmap > > for it. > > > >> > >> Cheers, > >> > >> John. > > And just when I hit send I thought of something else. > > Instead of the initial sync when creating a raid the bitmap could just > mark all blocks as unused. Much faster raid creation. A filesystem-coexist mode could also do this, by simply refusing operation until such a time that a filesystem is detected, or i suppose in worst case, mounted... > > MfG > Goswin > -- > 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
