On 2011-08-10, at 12:34 AM, Ric Wheeler wrote: > On 08/09/2011 06:52 PM, H. Peter Anvin wrote: >> Hi all, >> >> This is something I've wanted to see for a very long time, and it >> finally occurred to me that perhaps I should say something about it! >> >> It would be a very nice thing to have a flag to e2fsck, presumably -z, >> to zero out any unused data blocks, inodes and so on. The goal is to >> minimize the amount of space required after compressing a virtual disk >> image or similar, and to make sure any non-data isn't lying around. > > Do you need it to be in the fsck tool? > > If you have a sparsely allocated block map under your file system, doing a zero of all blocks could add hours for a big, slow S-ATA drives (2-3 hours for a 1TB drive). I think Ted has a tool that does this already. It should be relatively simple oo do, like "dd if=/dev/zero of=/mountpoint/temp_zero_file && rm /mountpoint/temp_zero_file. > An alternative for SSD's and devices that do TRIM/UNMAP would be to use one of the batched discard tools (that would make discarded data read back as zeroed). In fact, I thought Lukas has already made a tool for sending BLKDISCARD for all unused parts of the filesystem? Cheers, Andreas -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
