We have two of these, 4x2Gb WD red in Xraid, fully updated, still going well, suits our home / office network, two users. NAS-1 has 4 shares, one for office stuff and three for home media. All 4 shares are incrementally backed up weekly on different days by rsync to NAS-2. This has worked OK until we unknowingly backed up a corrupted file; lucky to get away with it for so long! Must get to grips with snapshots so we can maintain an historical record...lot of reading followed.
I preseme the NV+ uses copy on write. Our new (and now corrupt) file would be rewritten to NAS-1, only after the old OK version is copied to the snapshot, assuming this is active at the time? Thinking "what to be afraid of?" we opened up frontview and the manual.
I am getting the impression that NV+ snapshots are tailored just to cover the period of a backup, to cover the possibility of lost files if the share happens to be in use at the time. Keping a snapshot active is discouraged as it makes the system "serve data more slowly when keeping a snapshot". Snapshots can only be active for 24 hours, and the max time between them is also 24 hrs. Does a new snapshot after the 24 hours is up delete the old one? Do we need a 24 hourly share-snap full backup job to maintain an historical record? We are now becoming alarmingly confused again....
We'd be very appreciative of some guidance, and or useful links (I couldn't find anything relating to NV+)
I've never seen much written on the legacy NAS snapshot feature either. The underlying file system is ext, which has no snapshot facility - so I think the snapshot must be based on LVM (using lvcreate --snapshot). This would store the differences from the master volume, and it does use copy-on-write.
Note that snapshots aren't really backups, since they require the main volume (or share in the case of OS-6) to be intact to use them. But they can be handy for rolling back to previous versions.
Overall, the snapshot features in a new OS-6 NAS are much more flexible than your legacy NV+. You can configure snapshots on a share-by-share basis, you can have multiple snapshots, and you have control over retention. So if you want to build snapshots into your overall backup strategy you might consider getting a new OS-6 NAS. It would also be a lot faster than your NV+ (and it uses SMB 3.0, so it won't be affected by Microsoft's deprecation of SMB 1.0).
Hi! Thanks for your comments, however as the current NV+ are working (and fast enough for two), I was hoping to avoid expenditure, now I am in the twilight of my years.... I think NV+ could have some snapshot selectivity if we changed to Raid5, when each current share could become a volume (not tried, but as I understand it) and so individually snapshottable. Not much point if we can't fathom out if snaps are any use to us. Yours hopefully....
Not much point if we can't fathom out if snaps are any use to us.
I don't think they are actually. Their purpose wasn't to protect against corruption of files. Rather they were intended to ensure that a share backup is coherent. For example, if you are backing up a live database you want to make sure that the database files aren't changing while you are backing them up. If they were to change, the database wouldn't be usable.
The manual sugests that with Flexraid RAID5 you can have up to 4 volumes so presumably a different snapshot routine for each.
I get the point about ensuring coherent backups if shares are in use at the time. However, confusingly (for me at least) all the general reading I found about snapshots talks about the ability to go back in snapshot history to secure an earlier version of a changed file. I presume (?) that in Netgear terminology the snapshot would have to be "active" for some time, and that a new snapshot would not overwrite the last.
The manual sugests that with Flexraid RAID5 you can have up to 4 volumes so presumably a different snapshot routine for each.
You can have 4 RAID0 volumes. But RAID5 requires at least three disks in the volume.
There is an old rsnapshot add-on that might come closer to what you are looking for. I've never used it, and haven't seen any posts about it here for several years. It might need to be configured with ssh, not sure. https://community.netgear.com/t5/Community-Add-ons/Rsnapshot/td-p/643744
