On 05/07/2010 10:05 AM, Andrew Junev wrote: > Hello All, > > I was moving my filesystem to a new disk with 'cp -ax' command (as > root). It completed with no error messages, but I can see some > difference between the old and the new filesystems when using df: > > # df > Filesystem 1K-blocks Used Available Use% Mounted on > /dev/mapper/vg_mythbackend-wd20eads > 1922859824 1791862788 33321364 99% /newdisk > /dev/mapper/VolTerabytes00-Data00 > 1922868016 1793705984 51021168 98% /olddisk > > > My new filesystem uses ext4, while old one was using ext3 - can that > be somehow related?. I fact, I don't see how it can affect the used > space reported, since block size is 4K for both... > > I'm pretty sure I stopped most of the processes, so there was none that > could write to original filesystem while files were copied. Well, > maybe I missed something... > > Is there an easy way to check which files are there on the old > filesystem, that do not exist on the new one? These small variations are most likely caused by the differences in on-disk layout between ext3 and ext4. Ext4 is an extent based file system as opposed to ext2/3 which use indirect block pointers to describe the layout of a file's data blocks on disk. These indirect blocks consume some of the available space in the file system (they are part of the metadata overhead) meaning that storing a file in an ext3 file system may consume more disk blocks than storing the same data on ext4. Have a look at the ext4 wiki and kernelnewbies ext4 articles for more information: https://ext4.wiki.kernel.org/index.php/Main_Page http://kernelnewbies.org/Ext4 The exact numbers will depend on the size of files, fragmentation levels and the allocation patterns exhibited by the use of the file system so you can't say for e.g. ext4 is 14.159% more space efficient than ext3 as a hard rule but results like the ones you are seeing are not surprising. As other posters have commented, if you want to ensure that the directory structure and file content is correct on the new volume you should compare file lists or checksums to be confident all your data is there. Regards, Bryn. -- users mailing list users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe or change subscription options: https://admin.fedoraproject.org/mailman/listinfo/users Guidelines: http://fedoraproject.org/wiki/Mailing_list_guidelines
