Re: How to optimize the cloning of a disk with a big empty ext3 partition?
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On Fri, 2009-06-19 at 21:33 -0400, Theodore Tso wrote: > On Fri, Jun 19, 2009 at 04:42:54PM -0700, Gregoire Gentil wrote: > > Hello, > > > > I need to duplicate a huge number of identical 8GB SD cards on which I > > have 1GB of data at the beginning of the disk on various partitions and > > then a 7GB ext3 partition which is rather empty (just a few MB of data). > > > > The duplicator device enables me to select which sectors I can > > binary-duplicate. I would love to divide by 8 my duplication time, by > > duplicating only the first GB and then the beginning of the 7GB ext3 > > partition. > > > > When I do a mkfs.ext3, I see that the super-block is written to various > > locations of the partition which is not good for the optimization I > > would like to do. > > The metadata for ext3 is scattered across the disk; it's not just the > superblock, but it's also parts of the inode table, and bitmap > allocation blocks, which must be initialized. > > It's possible to determine the list of blocks that need to be > initialized, but it's going to be a rather long list. If you need to > type the list of sectors into your duplicator, it's probably not > practical. If on the other hand you can feed it a file with a set of > sector numbers, you could extract that list of blocks in use from the > filesystem (which listed by dumpe2fs, although not in the most > convenient format), and convert it to sector numbers counting from the > beginning of the disk (as opposed to block numbers counting from the > beginning of the partitions), and then feed the whole long list of > sector block ranges to your duplicator device. > > - Ted Ted, Many thanks for the explanation. It's what I was afraid of! Grégoire _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
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