My measurements are based on FreeBSD version 4.4 (perhaps 4.3), a 4.4BSD descendant which creates cylinder groups of 32768 blocks (32MB) by default. FFS has evolved since the papers from the eighties. I just repeated the experiment, on a not quite virgin disk, with a 240MB file. It shows that FreeBSD allocate 16MB in every cylinder group. The first run of indirect blocks is broken up probably because of other files. The other runs of indirect blocks are pretty consistent and span about 17392 blocks each. Below is icat -v output, which shows the block numbers for inode, indirect and data blocks. Wietse fs_read_block: read block 262176 offs 268468224 len 8192 (inode block) fs_read_block: read block 17025112 offs 17433714688 len 8192 (data block) ... fs_read_block: read block 17025200 offs 17433804800 len 8192 (data block) fs_copy_indir: level 1 block 4444896 fs_read_block: read block 4444896 offs 4551573504 len 8192 (disk address block) fs_read_block: read block 17025208 offs 17433812992 len 8192 (data block) ... fs_read_block: read block 17058992 offs 17468407808 len 8192 (data block) fs_copy_indir: level 2 block 30244872 fs_read_block: read block 30244872 offs 30970748928 len 8192 (disk address block) fs_copy_indir: level 1 block 30245888 fs_read_block: read block 30245888 offs 30971789312 len 8192 (disk address block) fs_read_block: read block 30245896 offs 30971797504 len 8192 (data block) ... fs_read_block: read block 30262272 offs 30988566528 len 8192 (data block) fs_copy_indir: level 1 block 30277640 fs_read_block: read block 30277640 offs 31004303360 len 8192 (disk address block) ... fs_read_block: read block 30295032 offs 31022112768 len 8192 (data block) fs_copy_indir: level 1 block 30310408 fs_read_block: read block 30310408 offs 31037857792 len 8192 (disk address block) ... fs_read_block: read block 30327800 offs 31055667200 len 8192 (data block) fs_copy_indir: level 1 block 30343176 fs_read_block: read block 30343176 offs 31071412224 len 8192 (disk address block) ... fs_read_block: read block 30360568 offs 31089221632 len 8192 (data block) fs_copy_indir: level 1 block 30375944 fs_read_block: read block 30375944 offs 31104966656 len 8192 (disk address block) Wietse ----------------------------------------------------------------- This list is provided by the SecurityFocus ARIS analyzer service. For more information on this free incident handling, management and tracking system please see: http://aris.securityfocus.com
This archive was generated by hypermail 2b30 : Thu Aug 08 2002 - 03:16:46 PDT