# Backup using Raid 1



## khowie-shaw (Aug 13, 2019)

Hi,
I recently read on this site that you shouldn't rely on Raid for a second  copy of photos.  Can someone please explain why?  I recently added a network drive with 2 x 4TB drives that are configured to Raid 1 (mirrored).  This provides 2 separate drives containing identical copies of each other.  Why would this not be a good isea?


----------



## mcasan (Aug 13, 2019)

RAID 1 data drive only helps availability of the contents on the data drive, not the boot drive, or the backup driver or other drives.    To me RAID 1 for data makes sense only after first addressing complete system backups onsite and also complete backups offsite (via cloud or rotating drives to another location such as a bank vault.     Then RAID 1 simply means in theory no interruption of your work if one of the RAID drives dies.   I imagine there will be an interruption when you do swap the bad drive for a new one and have the RAID controller update the new drive from the old one.  

Others persons will indeed have other thoughts on this.


----------



## clee01l (Aug 13, 2019)

RAID is not backup.  If you need 7X24 uptime on your data, then a RAID solution is useful.  
Changes that you make on one RAID Volume get mirrored on the other.  If one volume fails, then all of the data is on the other volume.  However,   If you make a mistake and delete or overwrite some files, that mistake is replicated on the other volume and you can't recover.


----------



## LRList001 (Aug 13, 2019)

clee01l said:


> RAID is not backup.  If you need 7X24 uptime on your data, then a RAID solution is useful.
> Changes that you make on one RAID Volume get mirrored on the other.  If one volume fails, then all of the data is on the other volume.  However,   If you make a mistake and delete or overwrite some files, that mistake is replicated on the other volume and you can't recover.



And if the unit develops a damaging fault, is stolen, hacked, catches fire etc. you lose the lot.

In the UK, after an oil storage depot blew up a few years back, the advice for commercial business continuity  backup is a minium of five miles separation, with 20 preferred.  There were businesses with perfectly good backups in their fire-safe on the site, but as the site was too dangerous for anybody to visit for days, there was no access to that data.  Tricky for the payroll company.


----------



## Linwood Ferguson (Aug 15, 2019)

Backups need to be, probably among things I am omitting off the top of my head.... 

1) Faithful and complete copies (and include something to verify that) 
2) Versioned (able to recover to point in time) 
3) Offline
4) Tested regularly 
5) Automated (because humans cannot be depended on to remember to back up)

Most people fail to have most of these features.

Raid (any raid) fails at least 2, 3, and 4.

Note that ransomware requires (3) and often (2).   Having your backup copy plugged in when malware strikes just lets it encrypt both the original and the (hopefully just 'a') backup.


----------



## LouieSherwin (Aug 15, 2019)

Ferguson said:


> (2). Having your backup copy plugged in when malware strikes just lets it encrypt both the original and the (hopefully just 'a') backup.



Excellent point. I had not thought of that.

-louie


----------

