We're about to pull the trigger on a ReadyNAS 312 with either two 2TB or 4TB drives. We have about 290GB of data files. Ideally we'd like to have daily snapshots, but I'm unsure how much data a snapshot takes. If I go daily, does that mean each snapshot will have 290GB of data in it, and I'd get about 5 snapshots before pruning started? Thank you.

It's wrong to think of the snapshot as a backup. I think the support agent gave you misleading information at best. The answer to your question depends on the file churn after the snapshot is created.Let's use 100 10MB files in a share as an example, and assume no file fragmentation at the start.When you first make a snapshot it actually takes no space. All the datablocks in the snapshot are shared by the main share and the snapshot. So there is 1000MB total: 1000MB in common; 0 MB only in the snapshot; 0 MB only in the share.Now imagine that fifty 10 MB files are deleted on the main share. The original datablocks remain in the snapshot, but are no longer shared. So there is 1000MB total: 500MB in common; 500 MB only in the snapshot; 0 MB only in the share. Furthermore, imagine that one file is completely changed in the main share. Again, the original datablocks end up in in the snapshot alone, and we have 10MB of more total space. So there is 1010MB total: 490MB in common; 510 MB only in the snapshot; 10MB only in the share. Now lets modify the first 5 MB of another file. That 5 MB can no longer be in common, total space goes up 5 MB. The version of the file in the main share is fragmented, the version in the snapshot is not fragmented.So there is 1015MB total: 485MB in common; 515 MB only in the snapshot; 15MB only in the share. Now lets add 10 new files of 10 MB each to the share. These aren't in the snapshot, but only in the share. So there is 1115MB total: 485MB in common; 515 MB only in the snapshot; 115MB only in the share.

If the usage on the volume exceeds 95% the oldest automatic snapshots will be removed to get the volume usage back below 95%.

mdgm wrote:If the usage on the volume exceeds 95% the oldest automatic snapshots will be removed to get the volume usage back below 95%.Yes, I forgot to mention that. It's much better not to let the NAS get that full of course.

I think "previous versions" is a very nice feature ReadyNAS feature, and perhaps under-publicized. If you know what file you want to roll back, it is much faster/more convenient than browsing through a ton of snapshots.

Just want to share these articles below if in case have not yet came across with it since might provide you with usable info:http://kb.netgear.com/app/answers/detai ... erating-myhttp://kb.netgear.com/app/answers/detail/a_id/24478http://www.netgear.com/images/ReadyNAS% ... -76104.pdf

ReadyNAS 312 Need Help Understanding Snapshots

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BaJohn
Virtuoso
Jul 10, 2015
mdgm wrote:
The threshold is alterable using the shell not via the UI.
Corrected as it was misleading.. I was using the English settings in general, not specifically the 'Settings' options in the GUI.

mdgm wrote:
The threshold is alterable using the shell not via the UI.

StephenB

Guru - Experienced User

Jul 10, 2015

BaJohn wrote:
StephenB wrote:
In your case, you'd see all versions captured in your hourly snapshots. (Not sure, but I think you won't see duplicates, just distinct versions).
ALL snapshots are visible, NOT just distinct versions.

All snapshots are certainly visible. But I was talking specifically about what shows up on the "previous versions" right click, not about snapshots per se.

I have double-checked this, and only distinct versions show up in "Previous versions". I have a share with 35 snapshots taken over the past three months. Files that haven't changed over that period come up with "no previous version found". Files that have changed don't give me 35 versions to choose from, only the ones that are actually different. All these files are in all 35 snapshots.

BaJohn

Virtuoso

Jul 10, 2015

StephenB wrote:
All snapshots are certainly visible. But I was talking specifically about what shows up on the "previous versions" right click, not about snapshots per se.

I have double-checked this, and only distinct versions show up in "Previous versions". I have a share with 35 snapshots taken over the past three months. Files that haven't changed over that period come up with "no previous version found". Files that have changed don't give me 35 versions to choose from, only the ones that are actually different. All these files are in all 35 snapshots.

StephenB wrote:
All snapshots are certainly visible. But I was talking specifically about what shows up on the "previous versions" right click, not about snapshots per se. I have double-checked this, and only distinct versions show up in "Previous versions". I have a share with 35 snapshots taken over the past three months. Files that haven't changed over that period come up with "no previous version found". Files that have changed don't give me 35 versions to choose from, only the ones that are actually different. All these files are in all 35 snapshots.

Thanks for clearing up the ambiguity.

jason92s wrote:
I can't tell you how helpful that is StephenB. Makes perfect sense and I think Netgear should append this to their KB articles.

I wholeheartedly agree, and as I have mentioned elsewhere, hope none of the useful information in some of the posts is not lost in the transfer to a new forum.

StephenB
Guru - Experienced User
Jul 10, 2015
I think "previous versions" is a very nice feature ReadyNAS feature, and perhaps under-publicized.

If you know what file you want to roll back, it is much faster/more convenient than browsing through a ton of snapshots.
- CLHatch
  Luminary
  Jul 26, 2015
  StephenB wrote:
  I think "previous versions" is a very nice feature ReadyNAS feature, and perhaps under-publicized.
  
  If you know what file you want to roll back, it is much faster/more convenient than browsing through a ton of snapshots.
  Unfortunately, seems the "Previous Versions" feature has been changed in Windows 10 (or maybe in Windows 8, not sure). They now have you specify a location to "back up" to for the previous versions. So the snapshots are no longer available through the Windows Previous Versions feature.
  - OOM-9
    NETGEAR Expert
    Jul 30, 2015
    I am not seeing that issue on my Windows 10 install.
    
    Did you go into the share configuration on the ReadyNAS to enable the "Allow Snapshot Access"?
    That button does two things:
    1) mounts your snapshots to a folder so you can browse
    2) allows the functionality for "Previous Versions" in windows.
CLHatch
Luminary
Jul 30, 2015
I'm thinking what I might do is keep it as is with offline access turned on, but set up a backup to my 4TB data drive on my PC as you suggested. We currently don't both edit files in that share, but it is good to know that she can still access the files if the NAS is rebooting, etc, and they'll sync back to it once it comes back online.
- StephenB
  Guru - Experienced User
  Jul 30, 2015
  CLHatch wrote:
  I'm thinking what I might do is keep it as is with offline access turned on, but set up a backup to my 4TB data drive on my PC as you suggested. We currently don't both edit files in that share, but it is good to know that she can still access the files if the NAS is rebooting, etc, and they'll sync back to it once it comes back online.
  
  Makes sense to me. I like that better than depending on offline access as a backup.
  - CLHatch
    Luminary
    Jul 31, 2015
    StephenB wrote:
    CLHatch wrote:
    I'm thinking what I might do is keep it as is with offline access turned on, but set up a backup to my 4TB data drive on my PC as you suggested. We currently don't both edit files in that share, but it is good to know that she can still access the files if the NAS is rebooting, etc, and they'll sync back to it once it comes back online.
    Makes sense to me. I like that better than depending on offline access as a backup.
    Got it backing up those important files to my desktop. I installed DeltaCopy on my desktop, and did a rsync backup using that... saw it complained about a long filename, did some googling, then updated the rsync, ssh, and libraries in the install folder to the latest from cygwgin to fix that. Thanks for the advice.

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ReadyNAS 312 Need Help Understanding Snapshots

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