On Feb 07, 2007 16:06 +0530, Suparna Bhattacharya wrote: > On Wed, Feb 07, 2007 at 12:25:50AM -0800, Mingming Cao wrote: > > - disable preallocation if the filesystem free blocks is under some low > > watermarks, to save space for near future real block allocation? > > A policy decision like this is probably worth a discussion during today's call. > > > - is de-preallocation something worth doing? As discussed in the call - I don't think we can remove preallocations. The whole point of database preallocation is to guarantee that this space is available in the filesystem when writing into a file at random offsets (which would otherwise be sparse). Similarly, persistent preallocation shouldn't be considered differently than an efficient way of doing zero filling of blocks. At least that is my understanding... Is this code implementing the "uninitialized extents" for databases (via explicit preallocation via fallocate/ioctl) so that they don't have to zero-fill large files, or is there also automatic preallocation of space to files (e.g. for O_APPEND files)? Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - 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
