Linux 命令dump的压缩参数z用得好,能使打包文件小很多. 经试验, 我认为最佳的压缩参数应为: -z4 或 –z5

压缩级别 用时    原文件大小     压缩后的文件大小
-z2        5:13    1941.56MB       970MB
-z4        7:55    1941.56MB       357MB
-z5        7:56    1941.56MB       353MB
-z8        9:57    1941.56MB       351MB
测试如下:
#进入单用户方式：
#init s
[root@rh9 home]# df -k
文件系统               1K-块        已用     可用 已用% 挂载点
/dev/hda1              3091284   1951416    982836  67% /
/dev/hda3               774040     18564    716120   3% /home
none                     62996         0     62996   0% /dev/shm
/dev/sda1              3953036    671956   3080272  18% /mnt/a
/dev/sda2              4743808    665068   3837768  15% /mnt/b
/dev/sda3              5747940     32828   5423132   1% /mnt/c
#
[root@rh9 home]# dump -0uf /mnt/c/sysbak.dump /            (缺省：-z2)
  DUMP: Date of this level 0 dump: Wed Dec 13 15:26:43 2006
  DUMP: Dumping /dev/hda1 (/) to /mnt/c/sysbak.dump
  DUMP: Added inode 8 to exclude list (journal inode)
  DUMP: Added inode 7 to exclude list (resize inode)
  DUMP: Label: /
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 1869529 tape blocks.
  DUMP: Volume 1 started with block 1 at: Wed Dec 13 15:26:46 2006
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 100.00% done at 6310 kB/s, finished in 0:00
  DUMP: Closing /mnt/c/sysbak.dump
  DUMP: Volume 1 completed at: Wed Dec 13 15:31:59 2006
  DUMP: Volume 1 1988160 tape blocks (1941.56MB)
  DUMP: Volume 1 took 0:05:13
  DUMP: Volume 1 transfer rate: 6351 kB/s
  DUMP: 1988160 tape blocks (1941.56MB) on 1 volume(s)
  DUMP: finished in 313 seconds, throughput 6351 kBytes/sec
  DUMP: Date of this level 0 dump: Wed Dec 13 15:26:43 2006
  DUMP: Date this dump completed:  Wed Dec 13 15:31:59 2006
  DUMP: Average transfer rate: 6351 kB/s
  DUMP: DUMP IS DONE
[root@rh9 c]# dump -z4 -0uf /mnt/c/sysbak-z4.dump /dev/hda1
  DUMP: Date of this level 0 dump: Wed Dec 13 15:46:25 2006
  DUMP: Dumping /dev/hda1 (/) to /mnt/c/sysbak-z4.dump
  DUMP: Added inode 8 to exclude list (journal inode)
  DUMP: Added inode 7 to exclude list (resize inode)
  DUMP: Label: /
  DUMP: Compressing output at compression level 4 (zlib)
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 1869546 tape blocks.
  DUMP: Volume 1 started with block 1 at: Wed Dec 13 15:46:28 2006
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 68.45% done at 4265 kB/s, finished in 0:02
  DUMP: Closing /mnt/c/sys-z4.dump
  DUMP: Volume 1 completed at: Wed Dec 13 15:54:23 2006
  DUMP: Volume 1 took 0:07:55
  DUMP: Volume 1 transfer rate: 1541 kB/s
  DUMP: Volume 1 1988180kB uncompressed, 732275kB compressed, 2.716:1
  DUMP: 1988180 tape blocks (1941.58MB) on 1 volume(s)
  DUMP: finished in 475 seconds, throughput 4185 kBytes/sec
  DUMP: Date of this level 0 dump: Wed Dec 13 15:46:25 2006
  DUMP: Date this dump completed:  Wed Dec 13 15:54:23 2006
  DUMP: Average transfer rate: 1541 kB/s
  DUMP: Wrote 1988180kB uncompressed, 732275kB compressed, 2.716:1
  DUMP: DUMP IS DONE
[root@rh9 /]# dump -z5 -0uf /mnt/c/sysbak-z5.dump /dev/hda1
  DUMP: Date of this level 0 dump: Wed Dec 13 15:34:28 2006
  DUMP: Dumping /dev/hda1 (/) to /mnt/c/sysbak-z5.dump
  DUMP: Added inode 8 to exclude list (journal inode)
  DUMP: Added inode 7 to exclude list (resize inode)
  DUMP: Label: /
  DUMP: Compressing output at compression level 5 (zlib)
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 1869536 tape blocks.
  DUMP: Volume 1 started with block 1 at: Wed Dec 13 15:34:30 2006
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 66.81% done at 4149 kB/s, finished in 0:02
  DUMP: Closing /mnt/c/sys.dump
  DUMP: Volume 1 completed at: Wed Dec 13 15:42:26 2006
  DUMP: Volume 1 took 0:07:56
  DUMP: Volume 1 transfer rate: 1520 kB/s
  DUMP: Volume 1 1988170kB uncompressed, 723886kB compressed, 2.747:1
  DUMP: 1988170 tape blocks (1941.57MB) on 1 volume(s)
  DUMP: finished in 475 seconds, throughput 4185 kBytes/sec
  DUMP: Date of this level 0 dump: Wed Dec 13 15:34:28 2006
  DUMP: Date this dump completed:  Wed Dec 13 15:42:26 2006
  DUMP: Average transfer rate: 1520 kB/s
  DUMP: Wrote 1988170kB uncompressed, 723886kB compressed, 2.747:1
  DUMP: DUMP IS DONE
[root@rh9 c]# dump -z8 -0uf /mnt/c/sysbak-z8.dump /dev/hda1
  DUMP: Date of this level 0 dump: Wed Dec 13 15:55:39 2006
  DUMP: Dumping /dev/hda1 (/) to /mnt/c/sysbak-z8.dump
  DUMP: Added inode 8 to exclude list (journal inode)
  DUMP: Added inode 7 to exclude list (resize inode)
  DUMP: Label: /
  DUMP: Compressing output at compression level 8 (zlib)
  DUMP: mapping (Pass I) [regular files]
  DUMP: mapping (Pass II) [directories]
  DUMP: estimated 1869556 tape blocks.
  DUMP: Volume 1 started with block 1 at: Wed Dec 13 15:55:42 2006
  DUMP: dumping (Pass III) [directories]
  DUMP: dumping (Pass IV) [regular files]
  DUMP: 51.04% done at 3180 kB/s, finished in 0:04
  DUMP: Closing /mnt/c/sys-z8.dump
  DUMP: Volume 1 completed at: Wed Dec 13 16:05:39 2006
  DUMP: Volume 1 took 0:09:57
  DUMP: Volume 1 transfer rate: 1205 kB/s
  DUMP: Volume 1 1988190kB uncompressed, 719903kB compressed, 2.762:1
  DUMP: 1988190 tape blocks (1941.59MB) on 1 volume(s)
  DUMP: finished in 597 seconds, throughput 3330 kBytes/sec
  DUMP: Date of this level 0 dump: Wed Dec 13 15:55:39 2006
  DUMP: Date this dump completed:  Wed Dec 13 16:05:39 2006
  DUMP: Average transfer rate: 1205 kB/s
  DUMP: Wrote 1988190kB uncompressed, 719903kB compressed, 2.762:1
  DUMP: DUMP IS DONE
[root@rh9 c]# ls -l
总用量 4170476
-rw-r--r--    1 root     root      2191360 12月 13 15:33 home.dump
drwx------    2 root     root        16384 2006-12-13  lost+found
-rw-r--r--    1 root     root     2035875840 12月 13 15:31 sysbak.dump
-rw-r--r--    1 root     root     749850016 12月 13 15:54 sysbak-z4.dump
-rw-r--r--    1 root     root     741259949 12月 13 15:42 sysbak-z5.dump
-rw-r--r--    1 root     root     737181246 12月 13 16:05 sysbak-z8.dump
带压缩选项用：-z4 或 -z5