3 ms·

Probably because most people don't want their profile to be broken if their OS crashes or their computer powers off unexpectedly?

cortesoft 10y ago
If you miss a sync, your profile isn't going to be 'broken', just out of date.
- spullara 10y ago
  if it happens during the sync you could be arbitrirly broken.
  - deleted 10y ago
    [deleted]
  - avar 10y ago
    Only if the sync is the equivalent of: rsync [...] /dev/shm/.browser ~/.browser Instead of: rsync [...] /dev/shm/.browser ~/.browser.new && ln -sf ~/.browser.new ~/browser Or some such equivalent, i.e. doing the full sync and then atomically juggling a symlink around.
    - wolf550e 10y ago
      that creates many more writes to the ssd.
      - waterhouse 10y ago
        Does it? Consider this scheme: maintain two physical directories, one of which is current (and is named by a symlink) and the other of which is old. When doing a sync, you rsync the newest data into the old directory, then update the symlink. It'll probably result in somewhere between 1x and 2x the writes as the non-atomic single-directory scheme, depending on how well adjacent diffs combine. It will also result in twice the space used (barring some very clever filesystem).
      - rovr138 10y ago
        He should have used --link-dest= on his rsync. PREVIOUS_BACKUP=$(cat ./prev_backup) NEW_BACKUP=$(date +%F_%T) rsync --link-dest=$PREVIOUS_BACKUP /path/source /path/dest/$NEW_BACKUP echo $NEW_BACKUP > ./prev_backup This will copy /path/source to /path/dest/$NEW_BACKUP (which is a time stamped folder). But it will take into account the previous backup. If a file hasn't changed, it will create a hard link. If it changed, it will then copy the whole file. And that's it. Since it's the name is a time stamp. When you need to restore, just read ./prev_backup or just list the directory content, sort it and read the last entry.
  - derefr 10y ago
    This isn't really the sync daemon's fault; it's Linux's (or rather, ext4's, and the Linux VFS ABI's) for not supporting multi-inode filesystem transactions. NTFS has them; APFS will have them. Linux should add them too.
    - sitkack 10y ago
      The sync daemon could sync with hardlink and then rename which is atomic.
      - Filligree 10y ago
        That would require rewriting the entire directory.
        sitkack 10y ago
        hardlinks for the stuff not changed. Browsers of course, should move to append only file formats.

cortesoft 10y ago

If you miss a sync, your profile isn't going to be 'broken', just out of date.

spullara 10y ago
if it happens during the sync you could be arbitrirly broken.
- deleted 10y ago
  [deleted]
- avar 10y ago
  Only if the sync is the equivalent of: rsync [...] /dev/shm/.browser ~/.browser Instead of: rsync [...] /dev/shm/.browser ~/.browser.new && ln -sf ~/.browser.new ~/browser Or some such equivalent, i.e. doing the full sync and then atomically juggling a symlink around.
  - wolf550e 10y ago
    that creates many more writes to the ssd.
    - waterhouse 10y ago
      Does it? Consider this scheme: maintain two physical directories, one of which is current (and is named by a symlink) and the other of which is old. When doing a sync, you rsync the newest data into the old directory, then update the symlink. It'll probably result in somewhere between 1x and 2x the writes as the non-atomic single-directory scheme, depending on how well adjacent diffs combine. It will also result in twice the space used (barring some very clever filesystem).
    - rovr138 10y ago
      He should have used --link-dest= on his rsync. PREVIOUS_BACKUP=$(cat ./prev_backup) NEW_BACKUP=$(date +%F_%T) rsync --link-dest=$PREVIOUS_BACKUP /path/source /path/dest/$NEW_BACKUP echo $NEW_BACKUP > ./prev_backup This will copy /path/source to /path/dest/$NEW_BACKUP (which is a time stamped folder). But it will take into account the previous backup. If a file hasn't changed, it will create a hard link. If it changed, it will then copy the whole file. And that's it. Since it's the name is a time stamp. When you need to restore, just read ./prev_backup or just list the directory content, sort it and read the last entry.
- derefr 10y ago
  This isn't really the sync daemon's fault; it's Linux's (or rather, ext4's, and the Linux VFS ABI's) for not supporting multi-inode filesystem transactions. NTFS has them; APFS will have them. Linux should add them too.
  - sitkack 10y ago
    The sync daemon could sync with hardlink and then rename which is atomic.
    - Filligree 10y ago
      That would require rewriting the entire directory.
      - sitkack 10y ago
        hardlinks for the stuff not changed. Browsers of course, should move to append only file formats.