Do ReadyNAS backup jobs work like Time Machine? Specifically, do ReadyNAS backup jobs first create a local snapshot, which is then used to backup to an external drive? Like this:"Time Machine makes hourly snapshots of files and copies them to a backup drive."http://www.creativetechsupport.com/help/it/install/timemachine-inherit.html My concern is if I add files to a ReadyNAS device at the same time it is running a back up job to an external drive. Is this a good/bad idea? How does ReadyNAS handle this? Any tips on configurations to make this possible/better? etc? For example, is running an overnight task to backup files from a Mac/PC to a ReadyNAS run *at the same time* as the ReadyNAS is running a backup job to an external drive? Thanks

aaroam wrote: How can you write to the ReadyNAS while the ReadyNAS is making decisions at the same time about what to backup? Looks like a huge potential for conflicts to write to a ReadyNAS while it is backing up. The heavy lifting is all done by the BTRFS file system used by the NAS. The backup application itself doesn't need to worry about maintaining coherency while the backup is running - the file system takes care of that. All the backup job has to do is create the snapshot, and back it up. A somewhat simplistic explanation: When the snapshot is first created, the snapshot and share jointly "own" all the data blocks. That is, the metadata in the snapshot and in the main share both point to the same underlying data blocks. The creation is quite fast, and uses essentially no disk space. As data in the main share changes, the changed data is written to new data blocks (using the "copy-on-write" feature of BTRFS). The original blocks are preserved, and are still referenced by the snapshot metadata. The new data blocks are only referenced by the main share. Unchanged data blocks continue to be referenced by both the main share and the snapshot. The net result is that the snapshot always has the content that was in the main share when the snapshot was created. Changes only show up in the main share. Disk usage is the total of the original share contents plus any changes made in the main share after the snapshot was made. When the snapshot is deleted after the backup completes, data blocks that are only referenced by the snapshot are reclaimed as free space.

On a "push" backup (internal to external), which is what I believe you are describing, yes. I'm not sure if it does on internal to internal. That is an advantage of using a push backup. But the downside is that you have to make sure the backup device stays on for the duration of the backup, so powering it via a schedule is challenging.

Sandshark wrote: I'm not sure if it does on internal to internal. It would if you set up rsync, and make the destination the "remote" system. Sandshark wrote: But the downside is that you have to make sure the backup device stays on for the duration of the backup, so powering it via a schedule is challenging. Correct, so I just use the "pull" backup jobs and live with the risk. My backups are made daily (midnight), and it's very rare for something to be changing on the main NAS at that time.

Thank you for the clarification!Sandshark wrote:On a "push" backup (internal to external), which is what I believe you are describing, yes.Yes, I was describing a "push" backup (internal ReadyNAS to external drive) Sandshark wrote:But the downside is that you have to make sure the backup device stays on for the duration of the backup, so powering it via a schedule is challenging.What do you mean by "powering it via a schedule is challenging"? Any tips to make a "push" backup (internal ReadyNAS to external drive) run smoothly, if I'm backing up computers to RN overnight while backing up the RN to an external drive?

Thank you for the clarification! StephenB wrote:My backups are made daily (midnight), and it's very rare for something to be changing on the main NAS at that time.May I ask what happens when that "very rare" event occurs? Errors? Conflicts? Any tips to smooth the bumps? When do you backup to your RN? What if something (big) is backing up to your RN (or changing on your RN) when midnight hits?

Do ReadyNAS backup jobs work like Time Machine?

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Sandshark
Sensei
Jul 09, 2021
On a "push" backup (internal to external), which is what I believe you are describing, yes. I'm not sure if it does on internal to internal.

That is an advantage of using a push backup. But the downside is that you have to make sure the backup device stays on for the duration of the backup, so powering it via a schedule is challenging.
- StephenB
  Guru - Experienced User
  Jul 09, 2021
  Sandshark wrote:
  
  I'm not sure if it does on internal to internal.
  
  It would if you set up rsync, and make the destination the "remote" system.
  
  Sandshark wrote:
  
  But the downside is that you have to make sure the backup device stays on for the duration of the backup, so powering it via a schedule is challenging.
  
  Correct, so I just use the "pull" backup jobs and live with the risk. My backups are made daily (midnight), and it's very rare for something to be changing on the main NAS at that time.
  - RNUser76
    Aspirant
    Jul 10, 2021
    Thank you for the clarification!
    
    StephenB wrote:
    My backups are made daily (midnight), and it's very rare for something to be changing on the main NAS at that time.
    May I ask what happens when that "very rare" event occurs? Errors? Conflicts? Any tips to smooth the bumps?
    
    When do you backup to your RN? What if something (big) is backing up to your RN (or changing on your RN) when midnight hits?
- RNUser76
  Aspirant
  Jul 10, 2021
  Thank you for the clarification!
  Sandshark wrote:
  On a "push" backup (internal to external), which is what I believe you are describing, yes.
  Yes, I was describing a "push" backup (internal ReadyNAS to external drive)
  
  Sandshark wrote:
  But the downside is that you have to make sure the backup device stays on for the duration of the backup, so powering it via a schedule is challenging.
  What do you mean by "powering it via a schedule is challenging"?
  
  Any tips to make a "push" backup (internal ReadyNAS to external drive) run smoothly, if I'm backing up computers to RN overnight while backing up the RN to an external drive?
  - StephenB
    Guru - Experienced User
    Jul 10, 2021
    RNUser76 wrote:
    What do you mean by "powering it via a schedule is challenging"?
    
    Sandshark and I are both backing up to other ReadyNAS. My backup NAS are on a power schedule, so they only turn on when its time to do the backups, and shut down after they complete.
    
    What is challenging about "push" backups is that the backup NAS has no idea when the backups will finished. So they don't know when to shut down.
    
    That won't affect you if you are backing up to external drives.
    
    RNUser76 wrote:
    
    Any tips to make a "push" backup (internal ReadyNAS to external drive) run smoothly, if I'm backing up computers to RN overnight while backing up the RN to an external drive?
    
    If you are in the middle of backing up a computer when the ReadyNAS backup starts, you won't get coherent results on the external drive.
    
    So you'd want to start the external drive backup first. Then you won't get the most recent computer backup, but the external drive will have coherence (not catching any backups in the middle).
    
    There is a bug with push backups at the moment, so you'd want to avoid 6.10.4 and 6.10.5 firmware (using nothing newer than 6.10.3).

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Do ReadyNAS backup jobs work like Time Machine?

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