On Mar 30, 2006 11:22 -0800, Mingming Cao wrote: > I made a kernel patch to allow a file to specify which block group it > wants it's blocks to allocate from(using ioctl to set the goal > allocation block group). I set the goal block group falls to somewhere > >8TB, and did dd tests on that file. Verified this with debugfs, the > allocated block numbers are beyond 2**31. > > Also before run fsx tests, created many directories (32768 at most:) and > verified one directory's inode is located in block group >8TB space. So > when we do fsx test on files under that directory, we are > creating/testing files >8TB. While useful, I don't think it is critical. As you mention, it is possible to do this by creating a lot of directories, though it might be tedious (need over 16k directories for a 2TB filesystem, 64k for an 8TB fs). Also, since this increases the allocation for each inode's reservation from 16 bytes to 20 (really 32 because it is in a slab), it might have a small performance hit. If it was available under some sort of compile-time configuration option it might make sense for developers. Cheers, Andreas -- Andreas Dilger Principal Software Engineer Cluster File Systems, Inc. - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
