# How safe are NAS server?



## drmaxx (Mar 6, 2011)

Since a while I am trying to evaluate a nice backup system that keeps my data reasonably safe. I am mostly worried about hardware failures and portability - which are in my experience the most important point of failure for computers. Let's ignore for the sake of simplicity all the other terrible things that can happen to your system, e.g. the house burns down, ....

So, I am thinking about some Raid5 or DroboFS setup - which will definitely satisfy my need for security against HD failure. However, what happens if the NAS box breaks? Is there a way to recover the data from the disks even if I don't have access to the original hardware anymore (e.g. after 5 years of service...)? The data is certainly still on the HD - but so far every NAS set-up I read about requires the formatting of the HDs before they can accept the new disks. 

Is a NAS a safe storage medium or do I need a second backup NAS?


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## clee01l (Mar 6, 2011)

A NAS is (usually) a small dedicated LINUX computer that consists of a hardware controller component in addition to one or more HDs.  In size it is not much bigger than the disks that are contained within. There are two potential points of Hardware failure.  If one of the several HDs fails, no data is lost if the HDs are configured as some form of RAID. If the controller fails, the data might be locked into a unique RAID format that can not easily be read unless the disk can be plugged into an identical RAID Controller.  

RAID does not mean NAS exclusively. Nor is a NAS limited to a RAID Format.  RAID requires at least two matching disks.  RAID1 is the lowest level of RAID that permits recovery is a Disk fails  It is essentially mirroring of one disk onto the other.  RAID5 requires 4 disks and any one can fail with out incurring data loss. 

You are wanting to have a redundant copy of your critical data stores on another computer possibly in another location.  A NAS can do this. RAID1 with two disks is probably the cheapest and easiest to set up if you have a home network. You can get a 2X1TB Netgear Stora for ~$275.   I would not consider a NAS portable since the unit usually is up and running 7X24X365.  With a device like the Netgear Stora, you can access your data anywhere you have an internet connection  (if you want to share images without going through a service like Flickr).  

It is possible to maintain a NAS in a easily readable standard file format  (like LINUX XFS) if you do not go for a RAID formatted configuration.   If you recognize the risks associated with RAID, and don't rely on a RAID unit as you only source for critical data, then I would strongly recommend starting with a RAID1 NAS or even a USB device.   I have 4 NAS units on my home network.  One is a Stora the others are older units that  I use for non critical data storage.  The Nice thing about a file server like the Stora is that it meets DLNA specifications and can be used to stream to a networks attached device like a TV.


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## drmaxx (Mar 7, 2011)

Thanks clee01l for the detailed reply. I simply can not get my head wrapped around the obvious fact that RAID setup is box specific and the drives can not be transferred to an other setup without loosing the data!!! This doesn't make sense for me.

It seems that I currently won't gain much by switching from my current system of external HD to a (NAS)box with all the drives consolidated. 

Thanks again for the help


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## clee01l (Mar 7, 2011)

It is not that the data can't be retrieved, It is just that the RAID format (especially stripped across multiple drives) is a different format.  It is not one of the common standards like FAT/FAT32, HFS (Mac), NTFS (Win) XFS/EXT3 (LINUX).  You simply can not attach it to your Windows, Mac or or even LINUX box and expect to read it without special software. I found this out the hard way when one of my NAS controllers failed.  Fortunately, I had an identical unit and was able to read the data by swapping drives.  Had I not been able to do that, I would have needed to a.) send it off to a data recovery shop, b.) purchase software for my Win7 computer or c.) find the right LINUX File system to mount the drive on my LINUX box.   Having learned this lesson, it still did not dissuade me from using my Netgear Stora NAS for back ups of my critical image masters. (FWIW, I think the Stora runs a custom version of MS Windows Server 2003).


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