6 ms·

this is the first I heard of this - why is this not a config flag ?

tedmielczarek 10y ago
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  If you miss a sync, your profile isn't going to be 'broken', just out of date.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.
gcb0 10y ago
because not losing data is infinitely better than saving your ssd life a couple years. we've had ssds for a long time now. still waiting for one to die on me. meanwhile I'm on my 27th dead spinning disk.
- Reason077 10y ago
  Some people are unjustifiably worried about SSD endurance. The reality is that even with fairly heavy use, most of them will far outlive the computers they're in. And their owners for that matter! I purchased my current SSD in March 2015 - it's a Samsung 850 EVO 512GB. It's done 7332 Power_On_Hours, and 36486573259 Total_LBAs_Written, which works out as just under 17 TB written, or about 31.6 GB/day. That kind of sounds like a lot. But let's put it in context. Even the previous generation of TLC NAND SSDs were recorded in endurance tests doing around 1 PETABYTE of writes before failing. The 850 EVO, with it's 3D V-NAND, should be capable of at least double that. For arguments sake, lets assume it will last for 1 Petabyte. I've written 17TB in 1.5 years, or 11.3TB per year. At that rate, this drive is still going to last at least another 90 YEARS. So is this really something to obsess over?
  - Retra 10y ago
    >The reality is that even with fairly heavy use, most of them will far outlive the computers they're in. I'm not sure what the lifetime of a computer is. In my family, we are still occasionally running machines from circa 1995. They work fine. When should I stop using my MacBook? The only reason I'd stop is if it died in a way that can't be cheaply fixed.
    - deleted 10y ago
      [deleted]
    - EpicEng 10y ago
      >I'm not sure what the lifetime of a computer is. In my family, we are still occasionally running machines from circa 1995. Pretty sure it's not 21 years, c'mon...

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.

gcb0 10y ago

because not losing data is infinitely better than saving your ssd life a couple years. we've had ssds for a long time now. still waiting for one to die on me. meanwhile I'm on my 27th dead spinning disk.

Reason077 10y ago
Some people are unjustifiably worried about SSD endurance. The reality is that even with fairly heavy use, most of them will far outlive the computers they're in. And their owners for that matter! I purchased my current SSD in March 2015 - it's a Samsung 850 EVO 512GB. It's done 7332 Power_On_Hours, and 36486573259 Total_LBAs_Written, which works out as just under 17 TB written, or about 31.6 GB/day. That kind of sounds like a lot. But let's put it in context. Even the previous generation of TLC NAND SSDs were recorded in endurance tests doing around 1 PETABYTE of writes before failing. The 850 EVO, with it's 3D V-NAND, should be capable of at least double that. For arguments sake, lets assume it will last for 1 Petabyte. I've written 17TB in 1.5 years, or 11.3TB per year. At that rate, this drive is still going to last at least another 90 YEARS. So is this really something to obsess over?
- Retra 10y ago
  >The reality is that even with fairly heavy use, most of them will far outlive the computers they're in. I'm not sure what the lifetime of a computer is. In my family, we are still occasionally running machines from circa 1995. They work fine. When should I stop using my MacBook? The only reason I'd stop is if it died in a way that can't be cheaply fixed.
  - deleted 10y ago
    [deleted]
  - EpicEng 10y ago
    >I'm not sure what the lifetime of a computer is. In my family, we are still occasionally running machines from circa 1995. Pretty sure it's not 21 years, c'mon...