On Mon, Nov 01, 2010 at 10:58:12PM +0000, Alex Bligh wrote: > High bandwidth I/O to the underlying disk is part of it - only one > reader/writer per file. We're really using ext4 just for its extents > capability, i.e. allocating space, plus the convenience of directory > lookup to find the set of extents. > > It's easier to do this than to write this bit from scratch, and the > files are pretty static in size (i.e. they only grow, and grow > infrequently by large amounts). The files on ext4 correspond to large > chunks of disks we are combining together using an device-mapper > type thing (but different), and on top of that lives arbitary real > filing systems. Because our device-mapper type thing already > understands what blocks have been written to, we already have a layer > that prevents the data on the disk before the file's creation being > exposed. That's why I don't need ext4 to zero them out. I suppose > in that sense it is like the swap file case. But why not just use O_DIRECT? Do you really need to access the disk directly, as opposed to using O_DIRECT? - Ted _______________________________________________ Ext3-users mailing list Ext3-users@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/ext3-users
