RAID is not a Backup... but snapshots are, kind of

[Markus.Schragner]

In almost every thread someone asking what raidlevel best fits his needs, there is always someone reminding that "RAID is NOT a Backup".
While this is true for traditional Raid sets, where filesystem corruption/virus/accidental deletion/other stupid stuff happens, i have a problem with this sentence in a Storage section of a [H] Forum.

Most of us in here should know what they are doing, more so when it comes to their precious data. When data is that Important, someone shoud consider by themselves that a protection against fire/theft could be a good idea. So offsite backups are the only option for this scenario.

But for me personally, the really unrecoverable stuff like family photos are the only things considered going offsite. This drastically reduces the amount of data, all fitting on a single Harddrive.

For other Media, the greater part like Movies/Music/Episodes, it is enough protection storing them on raidz2 and taking Snapshots.

Inmy opinion, the most critical precaution is NOT to work as admin/root on the Fileserver

What i would like to know,
1) how important is your data really to you and through what lenghts are you going to protect it?
2) What percentage of your whole capacity is really unrecoverable and how many MB/GB/TB is your overall capacity?

for me: 1) 95% Mediafiles just snapshotted on a Raidz2 array of 10x6TB Drives

2) <2TB personal files on 2 offline drives, rotating monthly between my home and parents home.

 

[Butcher9_9]

Most of us in here should know what they are doing, more so when it comes to their precious data.

I fear you have too much faith in humanity (or forum dwelling people).

The general saying " Raid is not backup" still stands, whether or not the data is worth backing up is a separate issue. Other than that I totally agree, backup important stuff more than rubbish.

Funny story about this issue.

Had a customer buy a Lacie Thunderbolt DAS and configure it in Raid5. He "backed up" his data to it (by backup he meant put the only copy on that DAS) . A HDD had a early death (pretty common) and then he pulled out the wrong drive killing the array. Anyway he was not very happy and he said he had lost $1.4mil worth of data that he had "backed up" to the DAS. (why the F would you put $1.4mil on a $2k consumer DAS and then only have 1 copy)

Many laughs where had in the office at his expense.

 

[Lord Nassirbannipal]

Neither RAID nor snapshots are adequate as a backup.

A snapshot doesn't protect against viruses, malware, or file corruption as all of that would be included in the snapshot.

The only way to protect against data loss/corruption is to have multiple external backups stored in multiple locations.

 

[_Gea]

For data security, you need both.

Snapshots at least ZFS read only snapshots protect against viruses, malware, deleted or modified files for whatever reason or
file-corruption so they are the most important way to keep current data and previous versions save and accessable.
In nearly all cases, this is what you need to regain data - paired with a solid raid-solution that allows a double disk failure with hot spare disks.

Snapshots do not help against a real disaster like theft, fire, overvoltage, hardware problems, sabotage or human errors.
For such a case, you need backups, best on external locations with snaps/ previous versions as well. Problem of backups:
They are mostly not up to date with data version of yesterday/ last week etc. So backup = mostly disaster recovery.

You can use near realtime replication to a second location to find a way to backup with a minimal delay
(down to some minutes even under load with large storage).