How to setup real time sync without file deletion?

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bantruong
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How to setup real time sync without file deletion?

Post by bantruong » Fri Jul 10, 2020 1:22 pm

I used the Hybrid Backup Sync application. I was trying to setup One-way Sync from Local to Remote using RTRR. In the Policy panel, when I select the schedule as Real-time, the Delete Extra Files option is ticked and greyed out.

Is there a way to alter this behavior? My reasons are:

Sync in Real-time: to have a copy of everything up to the last second.
Sync without file deletion at the Target: To salvage files after an accidental deletion at the Source.

It puzzled me that you can set no file deletion when the sync is non real time. The no deletion behavior should not be time sensitive right?

P3R
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Re: How to setup real time sync without file deletion?

Post by P3R » Fri Jul 10, 2020 5:05 pm

bantruong wrote:
Fri Jul 10, 2020 1:22 pm
Is there a way to alter this behavior?
None that I know of.

You can run a scheduled job with a high frequency but that's a workaround and not exactly what you ask for.
Sync without file deletion at the Target: To salvage files after an accidental deletion at the Source.
Real-time syncs aren't very good as backups for other scenarios than only exactly the one you ask about.

The Network Recycle Bin is intended for offering protection for your scenario within the NAS, at least for file deletions done via Samba, AFP, FTP and File Station.

Remember that when not doing file deletions it's easy to shoot yourself in the foot as you can more quickly than you expect fill up the sync destination.
It puzzled me that you can set no file deletion when the sync is non real time. The no deletion behavior should not be time sensitive right?
I guess they figured a real-time sync should only be used when an exact mirror is required.

Even more probable, there could be technical limitations preventing what you ask for. Let's say that you move a large set of data (hundreds of GBytes) within a shared folder. That will be almost instant (even from a networked client) as the data isn't physically moved on disk, only the pointers to the data need to be changed. But if you had the real-time sync without deletions that you want, all data would need to be copied from the original location to new and suddenly the real-time sync would be out of sync and not even close to real-time any more. If you then queue up more and more requests it would probably lead to a spectacular crash of the process... :wink:
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!

bantruong
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Re: How to setup real time sync without file deletion?

Post by bantruong » Fri Jul 10, 2020 11:26 pm

Great food for thoughts, thanks P3R. I guess the engineers have enough headage to deal with all cases including file pointer operations. The bottom line is it's not doable for me. Also thank you for reminding me of the Recycle Bin, I totally overlook the effect of it. So I would setup:
-a nightly backup (no deletion)
-a monthly sync (with deletion, a few hours after the last backup)
This way I have file archives for a month every month.

P3R
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Re: How to setup real time sync without file deletion?

Post by P3R » Sat Jul 11, 2020 4:12 am

bantruong wrote:
Fri Jul 10, 2020 11:26 pm
-a nightly backup (no deletion)
-a monthly sync (with deletion, a few hours after the last backup)
So you're gonna save two separate instances of every file plus all deleted files forever. Also you will regularly need to manually delete files so that your backup don't fill up completely.

I would instead recommend only a nightly but versioned backup where you allow deleted files to be deleted. Then you can select how many daily, how many weekly and how many monthly versions you want. The nice things about versions, apart from that you can save more of them, is that only changed and deleted files would use up additional storage space until the retention period is over.

Let's say that you save 6 daily, 3 weekly and 3 monthly versions. Then you would have 12 different backup versions of varying ages to restore from. Unless you have very much changes It would most probably not use up more storage than your scheme and you would not have the problem with that the storage eventually fill up and require manual deletions. Also any deleted file would always be available to restore within at least 3 months of the deletion.

Check out versioned backups, it's a wonderful and very useful feature.
RAID have never ever been a replacement for backups. Without backups on a different system (preferably placed at another site), you will eventually lose data!

A non-RAID configuration (including RAID 0, which isn't really RAID) with a backup on a separate media protects your data far better than any RAID-volume without backup.

All data storage consists of both the primary storage and the backups. It's your money and your data, spend the storage budget wisely or pay with your data!

bantruong
New here
Posts: 4
Joined: Thu Jul 09, 2020 2:32 am

Re: How to setup real time sync without file deletion?

Post by bantruong » Thu Jul 16, 2020 7:00 am

Thanks very much.

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