Anyone run a NAS (network accessible storage)? Question about RAID options...

[shponglefan]

Right now I have a 2 disc Synology NAS.  It's got dual 4 TB drives running RAID 1 (mirrored).  I've managed to completely fill it and I've got probably an additional 4 TB of data I want to store, plus future use.

I'm thinking of buying a newer 4 disc NAS; likely the Synology DS416play and set it up with quad 8 TB drives.  My debate is what RAID level to use.  RAID 1 probably doesn't make a whole lotta sense; I'd gain some fault tolerance, but lose half the space.

RAID 5 seems like it might be more ideal; I'd effectively lose 1 drive's worth of space but in theory the system could survive a single drive failure.  Another option might be to forgo RAID in favor of just a basic setup.  It's mostly used as a media server, so technically doesn't contain anything truly irreplaceable.  OTOH, losing a chunk of data in the event of a drive failure would be a PITA to re-acquire.

For those with home NAS units, how do you have it setup?

[nexusmtz]

As the storage space goes up, so does the amount of time that it would take to replace that data that you think of as non-critical.  I wouldn't want to lose my movie, music, karaoke, ISO, ROM, Amazon, Steam, or HumbleBundle libraries, even though I could probably replace all of them.

The NAS with all that on it is a QNAP 669L with 6x6TB drives in a RAID6 (24TB nominal space - really 21.8TB). I could have gone with RAID5, but I wanted to get some experience with RAID6. 'Unfortunately', as far as getting experience goes, it has been running fine for 15 months, including recovering properly from a UPS failure that cut power unexpectedly.

I think you'd be fine with RAID5 (on 6x8TB I might say RAID6), but make sure to enable whatever notifications the NAS offers so you don't overlook a failure.

As for whether you need RAID at all, you have to think about how you're using the NAS, how much trouble it would be to be without it, how quickly you can get a replacement drive/NAS in hand, and where else the data is stored.

If you have a nearby friend who has (or is also in the market for) a NAS, maybe you both keep a copy of the bulk of the data, and if you have a failure, you just take the fixed NAS to your friend's house to replace the shared data that way. Or you can make partial copies of libraries on portable drives and keep them at friend's houses. It's amazing how many friends would be willing to 'store and occasionally spin up' a 3TB drive full of movies. (OK, they'll spin them up daily.)

Whatever you choose to do, consider RAID a convenience and not a backup plan.

[ark_ader]

As the storage space goes up, so does the amount of time that it would take to replace that data that you think of as non-critical.  I wouldn't want to lose my movie, music, karaoke, ISO, ROM, Amazon, Steam, or HumbleBundle libraries, even though I could probably replace all of them.

The NAS with all that on it is a QNAP 669L with 6x6TB drives in a RAID6 (24TB nominal space - really 21.8TB). I could have gone with RAID5, but I wanted to get some experience with RAID6. 'Unfortunately', as far as getting experience goes, it has been running fine for 15 months, including recovering properly from a UPS failure that cut power unexpectedly.

I think you'd be fine with RAID5 (on 6x8TB I might say RAID6), but make sure to enable whatever notifications the NAS offers so you don't overlook a failure.

As for whether you need RAID at all, you have to think about how you're using the NAS, how much trouble it would be to be without it, how quickly you can get a replacement drive/NAS in hand, and where else the data is stored.

If you have a nearby friend who has (or is also in the market for) a NAS, maybe you both keep a copy of the bulk of the data, and if you have a failure, you just take the fixed NAS to your friend's house to replace the shared data that way. Or you can make partial copies of libraries on portable drives and keep them at friend's houses. It's amazing how many friends would be willing to 'store and occasionally spin up' a 3TB drive full of movies. (OK, they'll spin them up daily.)

Whatever you choose to do, consider RAID a convenience and not a backup plan.

The best advice you can get.  It is a bad idea to keep all your eggs in one basket.

[dkersten]

I forgo raid at home and go for capacity.  At some point in the near future I will probably invest in a second unit for backup.  The majority of my data is uncompressed blu-ray's for my home theater (20-35gb each), and while I own most of the blu-rays in the library, it takes a long time to rip them, so a loss of the ~100 I have so far would mean around 90 hours of time to replace.

I use raid 5 at work (actually raid 50 on my big SAN units), but that is a critical working environment, and anything I can do to reduce the risk of down time is necessary.

Figure a raid 5 system would cost you 25% capacity (in a 4 disk system) and gain you about 20% lower chance of losing your data to a hardware failure.  You gotta remember though, hard drive failures, even after several years, are pretty low.  I have seen reports based on tens of thousands of drives where 5 year averages were around 2%, and my personal experience would put it closer to 1.5%.  So when you lower your chance of failure by 20% of 2%, you dropped to a 1.8% failure chance.  Not exactly overwhelming.  And you are dealing with 4 drives, not hundreds, so when it comes down to it, you are rolling the dice anyway and 20% isn't going to amount to much of anything. 

My advice?  back up anything you can't replace and just go for capacity.

[ChadTower]

I use a single drive WD NAS at home and have for years.  It's mostly noncritical media (entertainment) with maybe 20% critical media (family video and photos).  The critical media gets backed up periodically on a second drive that is attached to the NAS via USB.  Backing up critical data this way should be fine as the odds of both drives failing at the same time are super low.  This is all on UPS for power protection.


I find these ~$200 single drive NAS units last around two years.  I have had a couple fail.  Interestingly I haven't had a drive fail yet.  It's always something in the controller.  Since they're using standard SATA drives the data is easily recovered in that case.


Granted, I'm not backing up 35gb blu rays.  My movies are all mostly still in the 1-2gb range with a couple here and there up to 4-5gb.  And I don't keep around hundreds of them like dkersten described.

[lilshawn]

can confirm, raid5 is the way to go here. especially since you are planning to go with the synology 4 drive unit. not much you can do with a 2 bay unit either mirrored or raid 0 striped.

with 4 drives you get the benefit of speed with disk striping on all drives (like raid 0) with the extra benefit of parity. so losing a drive is not a problem. rebuilding the raid is simple as replacing the drive. (results may vary)

going overboard would be a 4 drive raid 6 with double distributed parity. you could lose 2 drives. not really necessary unless it's mission critical info.

ALTERNATIVELY

you can go unRAID if your device supports it... or you roll your own server (easier than it sounds)

http://lime-technology.com/unraid-server/

[shponglefan]

Thanks all.  I have a feeling I'll end up going RAID 5.  I do want at least some fault tolerance.  The point about low probability of HD failure is well made; I've only had one HD myself fail in probably the last decade.

That said, with four HDs going I don't want to risk the chance that if one goes that I'll lose a chunk of data.

[behrmr]

You can do RAID5 with 3 drives.  If you use 8TB drives with drive 4 as  a hot spare and you'll yield 16TB of space.  If Drive 4 is in the RAID then you'll get 24TB of space and will sweat it out while you order a replacement drive. That's how most people do it.

I run RAID-1 at home and I have lost drives.  Hard drive failure does happen and you should plan for it.  I have had the same NAS unit for 4.5 years and have replaced both drives in it during that period of time with no data loss.

[shponglefan]

You can do RAID5 with 3 drives.  If you use 8TB drives with drive 4 as  a hot spare and you'll yield 16TB of space.  If Drive 4 is in the RAID then you'll get 24TB of space and will sweat it out while you order a replacement drive. That's how most people do it.

I guess my big question is how much space do I think I'll need.  16 TB seems like a lot, but so did 4 TB back when I set up my original NAS.  And especially since I am in the process of digitizing my media collection including a bunch of BluRays, I can see that space going quick...