怎样做系统备份

atai908

我想将系统做一次完全备份，用ufsdump做备份一定要在单用户模式下吗？一个文件系统一个文件系统的备份吗？刚学solaris,向各位高手请教

briangao

ufsdump doesn't need to be done under single user mode even through it is recommended that way. If your system is quiet, you may perform an ufsdump at multi-user level. This is especially true if you have ufs logging turned on. However you need to do that at your own risk. Here is the reason why it is better to perform an unsdump at single user mode. In UFS (Unix file system), for each file or directory you create, the OS is going to allocate an inode for it. The inode keeps the property information of the file or directory such as permission, size, and ownership along with the pointers pointing to the data blocks that actually contain the data. When you do an ufsdump, it backs up the inodes first and then the data. So if you are ufsdumping on a busy file system, let's say the ufsdump just backed up all 100 inodes but haven't started backing up the 100 files yet, a user logged in and created another file. When the ufsdump program comes back to backup the files, there are now 101 files. That results on your tape 100 inodes but 101 files. When you restore it, you will get file system inconsistency. So the official way to perform a clean ufs backup is:

go to single user mode
perform an fsck on your file system
unmount the file system ( not necessary for / /usr or /var unless you want to boot from cdrom to do it)
perform an ufsdump on the file system
re-mount the file system
You need to do this for each file system
back to multi-user level

One hint is that when you perform ufsdump of multiple file systems to the same tape, make sure you don't overwrite each other

susbin

"用ufsdump做备份一定要在单用户模式下吗？" --- No.
You can do it at run level 3 with snapshot.

Here is an example:
用<快照>功能自动备份 root 分区的脚本   
http://bbs.chinaunix.net/viewthread.php?tid=817959


"一个文件系统一个文件系统的备份吗？" --- Yes, if you use ufsdump.