I’m looking to spec out a new NAS. I have a relatively small media collection, that I hope to grow as I digitize more family VHS tapes etc. Right now I have around 4 TB of data, shared across an external drive and my internal ssd.
Whats the best path forward on drives in this new NAS? I’ve heard advice for buying one big 20TB drive over multiple smaller drives. What’s best for mitigation of drive failure? Is that even a concern? If I do multiple drives, should I use RAID?
I’m a little new to this. If you have resources for learning some best practices I’m all ears.
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RAID helps protect you from certain failures, and also allows you to add more storage inexpensively. Typically buying multiple small drives is cheaper than one larger drive, but you do have to buy at least one extra drive for failure.
You do need to plan for backups. RAID is not a backup, it doesn’t protect you from fires, computer failure, or accidentally deleting things. So a backup is necessary. Look into 3-2-1 backup solutions. At least 3 copies of your data, 2 different hardware types (like SSD and HDD), with at least 1 offsite copy.
People often keep their NAS at home, with a cloud storage provider as an offsite backup, and an external drive for local backup.
If you have the money, and a family or friend with space, you can buy multiple complete NAS solutions and back them up to each other.
You’ll have to find some kind of balance, ad it js a game of chance. You are always limited by number of slots in your server and current largest drive size. Then you are trying to balance price, speed, and durability.
For exampl, let’s say maximum amount of drives is 10, and maximum manufactured size is 50 TB. You probably don’t need 500 TB of storage that is in no way durable (if a drive dies, all the data on it is lost) and on a single server.
Death of drives is almost certain, two drives dying at the same time is quite low, so something like RAID 4, 5, 6, or 10 is a great start. Depends on how much storage you want, and then partition it accordingly. If you want 20 TB, you can do 4x 8TB in RAID 5, which yields 3x 8TB (=24) of effective storage.
Adding new drives is easy, and you are are always wasting just one drive. Then it depends if you want to sacrifice more space for more durability and switch to RAID 6 later on.
If you want even more storage, you can buy a micro server like ODROID H4+ and use it as network connected storage.
so something like RAID 4, 5, 6, or 10 is a great start.
Sorry - whilst most of your advice is great, this is a bit misleading.
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RAID 4 is very rarely used. It’s not a particularly safe or efficient use of striping, and was replaced by 5 shortly after it was invented.
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RAID 5 itself is now strongly discouraged for large arrays. (Google, “don’t use raid 5 for large arrays” for literally millions of pages explaining this, but it basically boils down to; “If a drive fails, the chance of a second drive failing whilst rebuilding is very high”)
But 6 is good if you’ve got enough drives and 10 (1+0) is also a fairly well regarded method for arrays of equal-numbered arrays.
With 4, you are correct, I went from top of my head back what we learned in high school 15 or so years ago. 5 is still better than nothing if you don’t have the resources to get one more drive for 6. Of course, the best is completely mirroring all stuff to a separate geo location.
It all boils down to willingness of spending money for more durability.
I’ve edited my comment to scratch R4. But R5 is still great for smaller arrays, and it is possible to, for example, have RAID 5 for movies, and RAID 6 for photos.
There are also combinations of RAID levels, like aforementioned 10. There is a nice comparison table with apparent drive requirements and fault tolerance on Wikipedia: https://en.m.wikipedia.org/wiki/Standard_RAID_levels
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I’m confused that you’re talking of buying 20tb SSDs - you must be very rich. Spinny drives are more usually used in homelab archive RAIDs since they are more cost effective at large size and RAID offsets some of the slowness associated with them. I’m going to assume you meant HDDs not SSDs, but the advice applies to both if I’m wrong about that.
Yes, you will want to RAID them. That gives some protection against individual drive failure, and yes, absolutely that is a concern. Whilst the chance of drives failing these days is less than it was, they still do fail without warning, even when relatively new, and because of the bigger sizes, the consequences are greater.
The alternative to RAID is JBOD (Just a Bunch Of Drives) which means lots of individual drives being presented, each with their true size, in multiple shares. Most folk don’t want that.
What RAID level you choose depends on:
- How many drives you fit. 4+ is good, and “more smaller” is better than “fewer larger” for safety, although the compromise is an extra 10watts or so of power per drive.
- Current best practice; Don’t use RAIDs 0 or 5 on large arrays. (0 means exponential increase of data loss. 5 is strongly discouraged due to rebuild times of large disks) 6 is good if you have enough disks. 1+0 (mirrored and striped) is reasonable, and the choice I made for mine.
- The hardware you’re using. Whether a linux PC or a bespoke NAS tool. Whilst the RAID levels are similar, the tools used vary a lot.
Notes:
- Also, be realistic about the space you need. Don’t over-size. Plan for 3-5 years growth, by then you’ll be wanting to change because of speed changes or drive failure.
- Some raid types slow down writing of data, some speed it up. Most are much faster at READing data.
- https://en.wikipedia.org/wiki/Standard_RAID_levels gives some explanation of the types.
- Google for “RAID CALCULATOR” for lots of free websites that allow you to see what space different sized drives give you with different RAID levels.
- Do not omit a strong backup strategy. RAID only protects against some types of hardware failure. A lightning strike, fire, rogue bios or software update, the host dying with an incompatible raid system. Buy disks for backups that aren’t in your RAID. (Good branded USB 3 disk and caddies are sensible). Automate backups if you can. Backup only what’s not easily replaceable.
- I wrote some thoughts on backups here.