I just had a strange idea for using an NAS system as backup location. It's not about backing up the NAS, but about backing up a central windows Server onto the NAS. I know that misusing RAID for Backup purposes is not a good idea since it's prone to errors and the full resync will degrade the harddisks used. So I've thought a bit and got this idea where I'd like some comments if this idea is good/safe or not.
Here's the concept: NAS System with at least 4 Harddisks on 2 seperate volumes. Backups done nightly from Server to NAS volume 1/2 (changes daily). Every day we exchange one full volume with another set of disks, that should cause no resync to happen.
When we have a 4 Bay NAS with 2 Volumes consisting of 2 Disks each, we can have 8 disks in total to keep backups for 7 days before they are overwritten. Each set of 2 disks that is not plugged into the NAS is stored in the safe, like it was done with tapes before.
I'm not sure if I missed any problem. I know about the complexity of this rotation system, but it worked out fine with tape drives before and is a condition that's not up for debate. A neccessary condition for the backup solution is that we can have at least one full backup from the last 7 days stored in a secure location.
When I say RAID is not a backup, I'm talking about when using it is a primary storage. People often mistake redundancy/high-availability for backup.
Now what you suggest is a bad idea. SATA connectors are designed for a limited number of pulls and will be damaged if you overuse them.
Handling disk drives bare you risk damaging them through ESD without realising it. They come in anti-static bags with good reason.
The OS is stored on the disks in a separate partition to the data volume. What you suggest could cause problems with this. Multiple volumes is not for users wishing to remove drives for backups but rather for those who do want X-RAID2 and would prefer a different RAID setup.
The backup functionality is in Frontview for a reason. It's not just there for show.
Also note that hot-removing disks (remove while NAS is on) is not a good idea if you value the data on them. If you hot-add disks they will be wiped.
I'm usually just a home user, but I was asked to help with a new backup for a small company, so I just started making some thoughts. I've never used an NAS (at least not in the Desktop box form factor) as primary storage for anything, even in my home setup the NAS is mostly used as the backup to the machines. Tape backups are getting too expensive, as the whole setup needs to be exchanged and the best offer with 500GB tapes is almost 3k EUR. Also the problem with that is it's not future proof and in a few years they'll have to exchange at least the tapes yet another time.
That's why I thought to ask around here, seems like some pretty decent experience with backups is available in this forum. Ok I just thought about the RAID wear-leveling stuff and didn't take into account the other issues that might come up with such a solution. So screw my original idea, I see the problems clearly now and understand it was a bad idea.
The NAS seemed like a great idea because it can easily integrate into the infrastructure and using the NAS as a backup target is rather easy to achieve. Any advice on what backup solution might fit the outlined scenario otherwise?
Does your data change by much say daily? Do you have a high speed internet connection?
Backing up NAS to NAS over the internet might not be a bad idea. This is certainly the way I'll be going once the NBN (National Broadband Network) in Australia is in place (could be several years away yet and the rollout would be stopped if there is a change of government).
Depends on what you consider a high speed connection, we're at pretty decent speeds for downstream, but the asynchronous in ADSL is a big A. We've got 1 Mbit/s upstream and 16 Mbit/s downstream, upgrades available are 1/50 and 2/100 or an SDSL line with 2 Mbit/s max for both up and downstream. The current amount of data is somewhere around 350GB and there's about 200 Megabyte per Week increased storage need. Not sure about how much data really changes (i.e. deletions and modifications to existing data), might be a few megs more, but that's nothing the connection couldn't handle. For an online backup service we'd probably need to send them a harddisk for the initial backup, otherwise the backup will block the line for 2 months straight.
instead of trying to rotate disks in/out of the nas, you should rotate USB disks, with a separate usb disk for every day of the week, or however needed.
With only 350g of data, 7 or 8 1tb drives should be very inexpensive and last a long time, at which point you could easily swap them for 2tb or greater whenever backup data becomes larger.
So the backup plan would be
server -> backup to nas nas -> backup to usb drive usb drives rotated in/out of safe and/or offsite
200MB a week isn't much. I'd get another NAS, do first backup on-site then take backup NAS off-site and backup over internet, at least with some of the data.
When you backup application data like Exchange Server, MS SQL Server, etc., the full backup data will be stored in a disk drive, say A to D. (It may be done automatically because of missing data in the backup location). In the consecutive incremental/differential/log backup schedule, the changed blocks will be backed up to the connected disk drive, which was with respect to the previous full backup schedule. When restoring this modified data cannot be applied to the full backup data.
Hence, those application data should be always done as full backup, which is waste of disk space. Also, consider the files newly added in the different full backups.
I suggest you to configure backup (possibly multiple full backups) to the NAS drive and then replicate that backup data to another drive.
In case of the main backup data was lost, the data is still available in the replication server. -- Aravind storegrid.vembu.com
