Hi All, I am presently doing a small POC with rsync for incremental backup and restore starategies.
I have come up with certain question down the line, can anyone help me with the explanation. Used the config and ideas from: http://www.mikerubel.org/computers/rsync_snapshots/ The commands executed on two machines in sequence Machine 1: root@Andruil:~# vim testfile root@Andruil:~# ls -lh testfile -rw-r--r-- 1 root root 71 2011-02-07 17:10 testfile root@Andruil:~# rsync -avh testfile vxadmin@192.168.155.151:/tmp --stats --progress vxadmin@192.168.155.151's password: sending incremental file list testfile 71 100% 0.00kB/s 0:00:00 (xfer#1, to-check=0/1) sent 147 bytes received 31 bytes 20.94 bytes/sec total size is 71 speedup is 0.40 Machine 2: vxadmin@vx64:/tmp$ ls -lh testfile -rw-r--r-- 1 vxadmin vxadmin 71 2011-02-07 17:10 testfile vxadmin@vx64:/tmp$ cp -al testfile testfile_bak1 vxadmin@vx64:/tmp$ ls -ilh testfile* 140822 -rw-r--r-- 1 vxadmin vxadmin 71 2011-02-07 17:33 testfile 140822 -rw-r--r-- 1 vxadmin vxadmin 71 2011-02-07 17:10 testfile_bak1 Machine 1: root@Andruil:~# vim testfile root@Andruil:~# ls -lh testfile -rw-r--r-- 1 root root 159 2011-02-07 17:33 testfile root@Andruil:~# rsync -avh testfile vxadmin@192.168.155.151:/tmp --stats --progress vxadmin@192.168.155.151's password: sending incremental file list testfile 159 100% 0.00kB/s 0:00:00 (xfer#1, to-check=0/1) sent 168 bytes received 37 bytes 45.56 bytes/sec total size is 159 speedup is 0.78 vxadmin@vx64:/tmp$ ls -ilh testfile* 140822 -rw-r--r-- 1 vxadmin vxadmin 159 2011-02-07 17:33 testfile 140823 -rw-r--r-- 1 vxadmin vxadmin 71 2011-02-07 17:10 testfile_bak1 As from this output i came to understand that when new update is written to the backup, the first backup file hardlink is destroyed and a new file is created. Is it how this works or am i missing anything here. I have performed these operations with large qcow2 images also. I came to a conclusion that this incremental concept is good, taking into consideration that only the delta is transferred. Is there anyway in which i can have only the delta of the original file be present at the backup location. something like 1. 1st backup is 100M 2. write 20MB to the original file 3. do a sync using hardlinks 4. i have 20MB file at backup location with the delta changes only. Mani -- K Manikanta Swamy +919059014442
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