Why isn't RAID/NAS a backup strategy

If important data is primarily stored on the NAS then you need to backup the data e.g. to a USB hard disk, another NAS or some place else.

RAID provides redundancy/high-availability (i.e. if any one disk fails, data remains intact) and is not to be confused with backup.

Take a look at Preventing Catastrophic Data Loss

You should preferably have 2-3 backup copies of important data on separate devices. NAS units can be used as an effective part of a backup strategy, but if data is only stored on the NAS and no place else it's not backed up.

raid arrays, nor nas are 'backup strategies' by themselves.

They can be part of a backup strategy. But if the raid/nas has the only copy of some data, then it is *not* 'backed up'.

Backup means having multiple copies, ideally in separate devices and locations.

Raid is a high availability solution, but raids can fail in many different ways. Raid 1 (mirroring), and raid 5 (stripe with parity) support a *single* disk failure without data loss. But, as has been repeated many many times here in this forum and others, often when a single disk fails, another is shortly behind it. When you replace a failed raid disk, the whole array goes through a rebuild process which highly stresses each disk. Older disks that are close to failing can easily go bad during this high stress period, and then you have a multiple disk failure involving data loss and alot of frustration.

Raid 6, which involves dual redundancy, can handle *two* disk failures, at the cost of reduced usable space. This can help provide extra protection during rebuild and/or expansion processes, but obviously bad stuff can still happen at the worst possible time.

Nas devices are simply a network shared storage (which may or may not involve raid, you can get single disk 'nas' storage boxes). This storage can be used for either primary storage, or secondary/backup storage. If you are using a nas to store all your music and video files, and you dont' have a copy of your files somewhere else, then they aren't backed up. If you are using a nas as backup storage (ie windows backup or mac time machine), then that would be considered backup because its not being utilized as primary storage and is a copy of whatever is on your desktop/laptop.

Other things that neither raid, nor NAS devices can protect against are; accidental/malicious deletions, theft, virus/malware, fire/floods/other natural disasters.

Something several experienced users here like to do, is have multiple nas devices. One used as a primary storage, that is then backed up to a separate device. Some even go as far as putting the 2nd (or third) device at a friend/relative/neighbors house to help avoid some of the above noted issues.

Another alternative is cloud backup, like dropbox or other cloud storage services.

You can also use a nas to 'backup' your external drive (if that is your primary storage), or you can connect an external drive to the nas, and backup from the nas to the external drive.

There numerous possiblities, but it all boils down to having multiple copies of your data in different devices and hopefully different places.

if backup IS the prime goal, then it would seem that something like cloud - maybe one of those services like _______ - might be a cheaper solution the owning one's own NAS/RAID/equipment.

Thank you.

I wouldn't suggest putting the only backup of important data in the cloud. A guy recently lost a lot of irreplaceable data when a hacker wiped his machines.

Also many users here have TBs of data. it's simply not practical to backup that much data into the cloud.

I thought that services like _______ were unlimited. I don't have TB's of data - just family pictures and videos and such.

Well I have 1Mbit upload (theoretically). Now that's say 100KB/s but more realistically I could probably get 60KB/s. Now assuming I maintained 60 KB/s constantly it'd take me over a few hundred days to backup 1TB of data. But I have several TBs of data so it'd take me years to backup my data over my internet connection. Simply not practical for me.

You'll have to decide what's a practical solution for you. I like having a combination of on-site and off-site backups.

NAS units are good as a place for shared storage so you can access the same collection of files on a range of devices on your network from a central location. The ReadyNAS units have a large range of features and can be used for a variety of purposes.

MarkNorgren wrote:
if backup IS the prime goal, then it would seem that something like cloud - maybe one of those services like Carbonite - might be a cheaper solution the owning one's own NAS/RAID/equipment.

For a lot of users (maybe even most PC users) it would cheaper to use a cloud service.

In my case, backup is one goal, but not the primary goal. The main reason I got a NAS was to consolidate my storage. We have 4 PCs, several media players, smart phone and a tablet. The multimedia and documents were scattered across the various systems, making it hard to keep track of what was where. The NAS solves that problem. Though I also back up the PCs to the NAS (and back up the NAS to my older slower NAS).

MarkNorgren wrote:
I thought that services like _____ were unlimited. I don't have TB's of data - just family pictures and videos and such.

Some truly are unlimited.

Carbonite isn't really. What they do is cut back your upload speed as you backup up more data.
http://carbonite.custhelp.com/app/answe ... allocation

The first 35GB of data can achieve upload speeds of up to 2 mbps (megabits per second). Between 35GB and 200GB of data, upload speeds can reach up to 512 kbps (kilobits per second). At 200GB or more of data, upload speeds are limited to around 100 kbps (kilobits per second).

I have a fast connection, and have backed up my NAS to the cloud (using CrashPlan's service). It took a couple of months to upload the full 6 TB of data. For me this is quite acceptable for disaster recovery, but I would rather have a local backup which can be recovered much more quickly. Also, I don't really trust the Cloud yet. A lot of the companies are new, and there will probably be a shake out at some point. And the cloud is vulnerable to failure too.

MarkNorgren wrote:
if backup IS the prime goal, then it would seem that something like cloud - maybe one of those services like Carbonite - might be a cheaper solution the owning one's own NAS/RAID/equipment.

Sure, if your only backing up a few gigs or less.

And having an unlimited and fast internet connection is highly recommend.

But if you are dealing with multi-terabytes of data, cloud storage is typically neither economical nor time-efficient.

To backup a few terabytes locally at gigabit connections, still can take several hours if not days.

To backup a few terabytes to the cloud would take months if not years, let alone the time it would take to restore (which you typically need much sooner if not right now).

So, for pictures and a few gigs of music/video, sure cloud could be an ideal solution. For mass storage, you can quickly run out of time and money trying to transfer to/from the cloud.

My primary NAS is my primary data storage. If a file is not on the NAS, it's just been downloaded and has not been copied from the download folder on the PC to the NAS. I usually don't do this immediately, but at some point during the day, for if I lost it, I can always download it again. Software downloads are copied over immediately.

As stated, my primary line of defense is the X-Raid2 configuration which preserves the data array in case of the loss of one disk.

My second line of defense is the secondary NAS which backs up the primary automatically every night starting at midnight via rsync. This is a very fast and effective process which synchronizes the files in minutes, not hours. Unlike the primary, there are no shares mapped to drives. However, because it has yesterday's files, if I accidentally erase on or mess one up badly, I can always copy yesterday's version of the file from NAS2 to NAS1 and start over. While this gives me very good protection should something happen to NAS1 it gives no protection in case of theft, fire or natural disaster to my home.

Therefore, an offsite backup is needed as well. In this case, I only back up the critical/important information, such as financial records and photos. In case of total disaster, I can get by without music and videos. However, I recently started an upgrade program for my external drives so that I can store more of this info in off site backup. I used to store this offsite backup in my desk drawer at work some 26 miles away, but since retirement, it is in my SD box at my bank, also some 20 miles away.

Depending on where you live, consider the unthinkable. If you are in the dry west, fires are a danger and can some up suddenly, so you may not have time to grab your NAS and beat feet. The four bay ReadyNAS units do have this nice handle on the back to make this possible (if you have time). If you are in tornado alley, you also may not have time to grab much before seeking shelter. In the Gulf and Atlantic coasts, we now have fairly good warnings about Hurricanes, so if you are prudent, you can find space for the NAS and a laptop before evacuating.

There is no cookie cutter or check list approach, for you have to plan what is best for you. I personally do not trust the cloud, you are dependent on other peoples hardware and business continuity. In the second post (by mdgm) in the link to Preventing Catastrophic loss, it tells the story of a Professional Organization that violated on of the basic rules of computing and lost data for hundreds of thousands of customers. BTW - this also applies to us with an NAS. Never start an upgrade without updating your backup first, although it works flawlessly in 99.99% of the cases, if you are the .01%, it will be your data at risk. Remember Murphy is always lurking.

Another rule is to never run off of the backup. If you need a file, copy it from the back up to the primary and then perform your operations on it.

Hopefully you now understand the most critical rule - never ever trust important data to only one device, be that device be a CD, DVD, Flash Drive, PC or NAS.

Hopefully, you will avoid joining the non-exclusive club I joined decades ago - the I Lost Data club. I have maintained backups ever since.

Thx, all, for the responses. I'm going to ponder the storage, back-up, NAS, and cloud conundrum