Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Even using RAID 1 do I still need a separate backup disk on another NAS?
Document: I have both this 2-bay DS213 and an older 4-bay DS400. They are reliable machines which can do much more than I want. Even with the wizards, I often find them still difficult to navigate - the menu system for the DSM software could use some more annotation and explanation.One cautionary note: if you start with one hard drive and then add another for RAID redundancy purposes, it can take DAYS to format the second drive.
Enabling the basic file sharing services is a breeze but setting up sharing on ur PC/mac usually requires searching the synology webpage for howtos if its your first time doing it. I am using it with two different 2TB hard drives (WD Red and Samsung Ecogreen) since thats what I had lying around and this mixed setup works without any problems with the synology hybrid raid (SHR). The disk checks and parity checks will roughly take overnight to complete and then my first backup took another whole night.
We still mostly get what we pay for in this world, and I believe a decent quality NAS, such as Synology DS213, is a good deal priced at $300 withOUT drives, meaning more like $600 including drives. Indeed, other NAS in its class cost well over $700. My setup including DS213 + 2 drives cost $616 for dual-3TB configured in RAID 1.
... and try to integrate via UPNP in your stereo sound system. Better than the DS212j but still there is a small quality loss when streaming FLACs (even when bypassing the router). Not happy with that but do assume that other NAS in that price range won't perform better (the DS212j was worse). Only option would be to go for the common RIPNAS devices offered by Linn, NAIM, etc. - which brings you to another price range.
I've 2, 2GB drives running RAID 0 (mirroring) with a headless CrashPlan client running. The device has enough power for my relative simple purposes but I don't think it would work so well if I turned on even half of the Synology's features. If you need high power opt for a more substantial and pricier Synology or other NAS. however for a feature rich and affordable home NAS this works great under a simple setup. Setup is pretty self explanatory though might be challenging if you're not technical at all.
Bought this NAS (about 4 months ago) for document storage at our church. Operating flawlessly.Added two 3TB drives and set up as RAID 1 (Mirrored). This is an awesome device. First, the web interface is insanely simple to use, yet powerful. We replaced a Buffalo NAS that was a pain to manage and is very secure. We have 20 folks that login from home and upload or retrieve documents they need for various ministry groups.
Does provide decent NAS services.Cons:  Have not had enough time to get it to work outside my house, so it's not portable at all, from what I can tell. Barely works with Plex. I thought my Macs were working well as a network backup target, but in fact they were not (mostly the fault of Apple, but this is a big reason I purchased it). I really barely use this now that I ordered a separate local disk for my Macs.
(Ended up with 2.6TB usable after auto-RAID/mirror)-Installed the Synology software and it was up and running.-Setup my home PCs to backup to this device using Crashplan, 'PC Load Letter' has a nice plugin for this.-Backing up my other non-changing content now. Easy to setup shared folders from the NAS device.-Lots of plugins available from Synology and others.
This NAS has met all of my needs so far. Serving media over DLNA throughout my house, acting as a Timemachine backup location, a Dropbox substitute, and allowing me to access all my files and information through iOS apps. The only downside is that it only has 2 bays which was obviously known at the time of purchase.I've been using it for more and more things lately and 6TB of storage is starting to fill up quickly. Guess I'll need to upgrade this unit pretty soon.
It cost more than I expected to spend and more than some comparable units if you only look at the spec sheet, but it works and works well with a rich software suite that promises more than I'm likely to need..  And, regarding opening the case for cleaning, I found this in the Synology forum:"It's not hard if you know the trick. You do not even need to remove the screws from the back.1. Remove the HDD cover and remove both HDDs.2.
Answer: The short answer is yes. To elaborate, RAID isn't a backup scheme but rather a sophisticated scheme for building in fault tolerance. In RAID 1, if one of the drives goes down (assuming a 2 drive array) the NAS system can rebuild the data from the information contained on the remaining good disk. Though there is a certain "redundancy" of the information contained in a RAID array, the repository is still treated as a single source of data--if you lose the source, you lose your data. Thus RAID isn't so much a data backup strategy as it is a hardware backup strategy. Your data is kept safe by making sure the storage hardware doesn't go down.Though RAID helps with the problem of data loss, it doesn't address the issue directly. The best way to guard your data is to have multiple repositories kept in different places. For instance, on my computer I have three data drives. One is the main data drive, and I use backup software regularly to ensure the other two always mirror the first. Beyond the local drives on my computer, there's also a NAS box in the family room that I backup to. Moreover, I also have data stored in the cloud. Services like Box, DropBox, SkyDrive, Google Drive, etc. provide a useful amount of storage space for free (anywhere from 2 to 10 GB). For data you simply can't afford to lose, there's no better place to store it than on the servers of some big information technology company like Amazon.Using this scheme I can lose two or three sources of data, yet my data isn't irretrievably lost as there are yet other sources to draw from. Compare this against a stand-alone RAID array. If the array is lost in a fire, flood, or even stolen, the data is gone for good (barring some miracle).So yes, you do need a good backup plan beyond the RAID array.Hope this helps.Michael P. Herbst