RAID 6 vs 10 vs hybrid vs other for 8 drive array

[Jataro]

Hi all,
I apologize if this is a major newbie question but I have not been able to get an answer by reading up on this. I want to set up a home media server, mostly for music, possibly for video too in the future. I'm probably going to get a synology 1812+. At the moment 8 drives is absolutely overkill but the cost increase going from a 5 drive to an 8 drive solution is relatively inexpensive. Also I think storage needs are growing rapidly and if I'm going to set this up then I might as well "future-proof" as much as possible.
So here's my problem. Since I will be archiving all of my digital music (mostly from CDs), and there's a lot of it, I want to reduce the risk of having to do it more than once. For this reason data protection/redundancy is very important to me. Also at data of this size (4-6TB) backing up to an external (non-RAID) source is going to be difficult (though I will try). I'm just not sure which RAID is the best one for me.
I'm going to try and summarize what I have read about the assorted RAIDS. Please correct me if I'm wrong and any opinions on what's the best option are really appreciated. Thank you!
Jat

RAID 5: RAID 5 is out since a single lost drive places the entire array at risk and I've read that during a rebuild the risk is higher. Also with large drives (1TB and above) I've read that the risk of a bad write increases to about 50% when using at least 4-5 drives. This means a rebuild is a coin flip of incurring a total loss due to a "write hole."

RAID 6 seems better since there are 2 copies of parity. Write speed is very slow, read speed is good. Has a "write hole."

RAID 10 is less space efficient but writes faster and supposedly has better data protection. I think it also does not have the "write hole" issue of RAID 5/6. The only major concern I have with RAID 10 is that loss of any of the RAID 1 pairs kills the entire array. In my 1 experience with drive failure it came because of a power outage while writing to a drive. So if it happens that that 1 pair is updating when some disaster strikes then I'm worried that I'd be SOL.

Lastly, it seems that RAID 5,6, and 10 all require you to have all of your drives from day 1. I don't really need all 8 drives right away so that makes the proprietary RAIDS seem great since they seem to allow you to add a drive without issue. I'm not sure if they require a redistribution of everything to do so and what the risk of failure in doing this is.

 

[Anteaus]

What about non-raid options. Raid has it's place but it isn't always the most elegant solution. Raid provides redundancy but it isn't a backup system.

For an HTPC, my personal choice would be to start with a matching set of drives, say 4 2TB drives. Put all your data on the first two drives and use the second two drives as backups. I'm not advocating Raid 1. Instead, use software like Beyond Compare to sync drives. The upside is that the backup drives will powerdown when not in use, thus providing energy saving as well as extending drive life. Also, since all drives are independent, one drive failure means simply replacing the drive and making a new backup.

I realize that raid is sexy because you can have more usable drive space with redundancy when compared to straight up backups, but as you've stated the added complexity comes at a heavy cost should things go astray. Also, you shouldn't use non-raid specified consumer hard drive in any raid array other than 0 or 1. Chance of failure is dramatically higher if you don't purchase drives designed for raid, and they can be costly.

 

[Jataro]

Hi Anteaus,

Thank you for replying. One thing I forgot to mention is that my plan is to run this from a mac mini. MAC because our household is all MAC. The mini so it can be located next to the HT. A tower is a consideration but Apple really charges a ton for those.

The configuration you suggest sounds pretty good. If you don't mind I have a few questions about it. Where are your data drives located? Are they internal or external? If they are external are they in a NAS? Do consumer level NAS devices usually allow users to set this up or are they really oriented towards RAID? Would read speed be sufficient for video (since it's pulling data from only 1 drive at a time)?

Again, thank you!
Jat

 

[Chapbass]

Personally, I suggest you take a look at Unraid by lime technology. You get a parity drive, similar to raid 5, but if more than one drive dies, you only lose the data on that individual drive. Also, no expensive raid controllers, just need to have the drives plugged in.

Check it out!

 

[Anteaus]

My primary drives are internal drives. Each internal drive has a matched size external drive that is used for backup purposes. Depending on how often I add or change data, I'll connect the externals, sync the drives then disconnect and put away the externals. It sounds like a hastle but I only do it every week or two depending on how often I add movies/music.

The mac-minis are cool devices, but definitely check all your options. Look at maybe a building a HTPC. Newegg has some really cool horizontal cases specifically for that and you will have more space for drives and whatnot and they will match with your HT setup. You'll get much more for your money. Good luck.

 

[bigi]

I recommend RAID6 with GOOD controller. As you may not be aware, HDDs often fail during array rebuild process. This makes RAID5 very bad in this respect.

RAID6 would hold fine in this scenario as it can tolerate 2 drive failures. Also, decide on a good backup strategy as RAID will not protect your data, it will only provide a better uptime of the system.

 

[VirtualLarry]

Google unRAID.

 

[Jataro]

I looked into unRAID very quickly, I'll have to go back to it tonight when I have more time. From my quick look, it seems like unRAID sets up a RAID 5,without striping, with parity localized to a single disc. Because there's no striping non used drives are not active, and if the array fails all data on non damaged drives are intact. The unRAID manual says it's slower than than a stripped RAID, any idea how much so (ie fast enough to stream)? Thank you!

 

[Jataro]

Thank you for the recommendation. I looked into unRAID. It looks like a great solution but I don't like that it can only survive 1 failed drive at a time. In their forums a lot of people have also complained that when a drive fails it's not always obvious leading to people not knowing for weeks or months. This had led to people losing their arrays because they didn't know about it in time.

Does anyone have any experience using either RAID 10 or synology's hybrid RAID? Any idea of average time to failure? Thank you again!
Jat

 

[zephyrprime]

Why on earth would you want to connect this to a Mac Mini? You might as well get a NAS rather than do that since it would be a cheaper and easier setup. Do you mean that the Mac mini is going to be connected to your tv?

Just get raid 5. You're over thinking this. The write hole problem isn't so bad. You don't lose all data you just lose the data in the stripes where the data is. In the real world, you may lose a few mp3 tops if you ever encounter the problem. Let's not pretend you media server is an enterprise server at Apple Corporate head quarters. The data on your computer isn't that important and since it's all media, it can be recovered from the original source discs.

I have a 5 drive raid 5 array built from a P45 motherboard. It's very cheap and easy. Wish I had maxed it out with 6 drives.

 

[Jataro]

The reason I'm connecting this to a computer is I'm using the computer as the main playback source for my HT/music. It works really well and at least for me is better and more convenient than a Netflix/DVD/CD player. Reason for the Mac mini is it's the cheapest Mac computer that apple makes, it's small, and we have an all Mac house so I don't have to buy all new software for a windows or linux based computer.

As for the value of the data, you're right it isn't the end of the world if it vanishes. However, I've got about 1000 CDs which are being individually ripped, converted, and some need metadata corrections. I'm not even 1/3 of the way through and it's taken me 3 months of random spare time to do this. It's a major PITA but it's worth doing, for me at least. All that being said I don't want to have to do it again so I'm trying to minimize the chance of that happening.

As for unRAID I would build one if they could make it able to survive 2 failed drives.

 

[zephyrprime]

You should always have a full back up. Raid is no substitute for backing up. Save money by not buying a synology 1812+ and buy additional hard drives to do offline backup to. That's how I roll.