On 29-03-2013 17:28, Greg Freemyer wrote: > On Fri, Mar 29, 2013 at 4:09 PM, Daniel Hilst <danielhilst@xxxxxxxxx> wrote: >> Suppose that I have two big filesystems, dest fs and source fs.. I want >> to copy whole source fs to dest fs, but I need to keep >> source filesystem online I can't mount source fs read only and copy.. >> >> The idea is, mount both filesystems "together", and make write/read >> operations go on this way >> Read operations: >> 1. See if data is already on dest fs, >> 2. If is then read data and bright back to caller (lets call this >> cold read) >> 3. If is not, then read file from source fs, put it on page cache, >> and change the backstorage of that page.. >> 3.1 So when this page get dirty or too old, it will be writed to >> dest fs >> >> The problem here is, I need to remap every data and metadata on >> step 3 (inodes and stuff), I think that read only data, isn't writed to >> disk, >> so in case of old page, this page would be freed from memory and >> not write to dest fs.. so I need read only pages to be forced dirty.. >> >> Write operations: >> 1. Write data to dest fs >> 2. Mark data as present on dest fs >> >> >> Also I need to know when copy is finished, so I need a tool to >> crosscheck both filesystems and say what was copied and what wasn't, and >> give me some percent of remaining unsynced data. When I get 100% of data >> in sync I can umount source filesystem and use its storage for other >> propose. >> >> The go here is move data online, where I can't bring data offline.. >> >> I'm a kernel newbie, I have just read a lot about page cache and VSF, >> but this seems possible, right? > > Are you looking for a pre-existing solution? Or you want to write something? > > Greg > I can do this with btrfs snapshots, I think LVM2 can do this with snapshots too... I was searching for something like that, but using a kind of VFS hack So I want to know if is possible, in theory, then I can start write something like that -- Follow the white rabbit! _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
