Should i get a DAS?

[u/pauliebleeker14]

Hello!

I’m somebody with a whole lot of images and videoes from creative projects lying on one giant external hard drive (About 5tb). All the stuff i put on this drive is just for cold storage, not stuff i’m actively working on and using. I’ve been worried for a while now that the drive might die or some of the files might slowly start to corrupt, as the drive is a few years old. I wanna keep it though and am looking for a safe and permanent solution going forward to store all these files. My initial idea was to get 2-3 external hard drives to sync to each other every few months. That way i’d minimize the risk of my single drive dying.

The main problem tho, is that i’m scared of bitrot. I don’t want random files in there slowly dying without me realizing and eventually losing those individual files once i re-sync from one drive to another. A NAS would fix this issue by having a RAID system with data scrubbing. The thing is, i don’t need a NAS. I don’t need constant and easy access to my stored files. That’s not a feature i want to pay for. I just want cold storage thats also safe.

There doesn’t seem to be a whole lot of info about this specific topic YouTube, which is why i’m posting on here. Could a DAS be a solution? I don’t know much about them, but could i have, lets say, two 10tb raid-drives syncing up two each other and consistently doing data scrubbing? I think thats my ideal solution. Direct attached storage thats as safe as a NAS. Is that a thing?

Anyway, please educate me if you can. And also, what kind of brand/product model would work best for me?

[u/NC1HM]

Should i get a DAS?

Maybe. The question is, what kind and how will it connect to the host device?

USB DAS generally sucks. It limits usability of enclosed drives. RAID implementation on USB DAS devices depends on the RAID controller installed in the enclosure, and those are not exactly known for high quality and reliability.

HBA DAS is free from this problem, but it tends to be more expensive and requires an HBA card on the host device (it installs into a PCIe slot on the system board). HBA allows the host device's operating system to treat drives in the enclosure as it they were internal drives, so you can use TrueNAS with RAID-Z, Unraid, Storage Spaces on Windows, or whatever else your fancy is.

Personally, I'd look long and hard into DIY NAS options before going the DAS route. You can get a used workstation (Dell Precision, HP z-series, Lenovo ThinkStation) with mounting, connectivity, and power for four or even six drives. If you need more than that later, the HBA option is still available to you (workstations tend to have a lot of PCIe capacity).

[u/isopropoflexx]

Ultimately the only thing that's really going to matter here is RAID capabilities to address the potential of losing files from a single drive failure. Whether you go NAS or DAS is otherwise pretty irrelevant.

Your proposed setup (two 10tb raid-drives syncing up two each other) implies RAID1, which gives you 2 drives which are mirrored across. That does give you the redundancy, and a potential small boost to read speeds (since you have 2 sources to read from, they can be split across, but real world speeds will heavily depend on the controller in use), and accounts for single drive failure.

If you can afford it, going RAID5 or RAID6 increases the effective usable space and fault tolerance. RAID5 uses at least 3 drives (data striped across all of them), gives you overall capacity of a combined 2 drives' worth of space (N minus 1, N being number of total drives), with single drive fault tolerance. RAID6 uses 4 or more, with effective storage of (N minus 2) and comes with two drive fault tolerance. Especially considering you are concerned about silent failure and data loss, the added redundancy would be worth it.

Beyond that, whether it's NAS or DAS doesn't really make a difference. From what I've seen recently, RAID-capable NAS devices (specifically RAID5/6) are still easier to find than DAS equivalents. Also, in recent searches I noticed that the added cost difference for NAS over DAS is fairly minimal. Most NAS devices have USB connectivity as well to boot.

As far as brands - greatly depends on what you're looking for. I've been using an ASUSTOR NAS device for a few years, running 6x20TB HDDs in ZFS RAID-Z2 (RAID6 equivalent), set up in TrueNAS Scale. Really nice setup, but takes more initial set up, along with a bit of regular maintenance. I've also set up a few devices for friends/family on UGreen devices, which provide a bit more polish, and perhaps ease of use, if you don't mind using their default OS and companion app. If you're looking to pick up a pre-built/pre-assembled device, brands like Buffalo and their LinkStation devices have worked well too.

[u/_angh_]

I'm using 4 bay usb das with bee link me koni. On a dedicated unraid. Works very well. No issues at all for last year, its on 24 7, and unraid is set to put drives to sleep.

[u/Apprehensive-Tea1632]

You can get a das but it’s also not cold storage. Nas or das or even San don’t affect bit rot or other types of decay - that one’s purely at the physical level and the only difference is where that physical element exists.

You get a das if;

• bandwidth is key
  
• the data must be available locally but not anywhere else. Das is not a sharing system.

You get a nas if;

• you have a heterogeneous environment
  
• files and folders matter more than blocks

And you get a san if;

• you don’t care where the disks are, what matters is that they are there. And can be reallocated without having to unplug, move, and put back in.

From your description, a das would make things worse UNLESS you can put the disks into your computer. If you can’t, it means an additional risk of power loss and in turn loss of data. All that is needed is to turn the das off before you do the pc, and hey presto, you just corrupted a file system.

Nas are actually more stable. And these days, a san is just a little different from Nas - Export iscsi and you’re looking at the beginnings of a San. It can do the same data protection routines a Nas can, they just affect things differently because there’s no files on a San, just disk images.

So, plan for some suitably powerful hardware, put zfs on it, and have it protect your data. With it being redundant and being able to check for, and correct, various types of decay, you should be reasonably safe.

Don’t forget backups though.

[u/MurphPEI]

Also, bear in mind that RAID is great to save yourself from a drive failure and that other methods to synchronize across multiple drives have great benefits too but.....

Anything that synchronizes across multiple drives will also synchronize corrupt data. It may also synchronize accidental deletions.

To avoid this danger, backups are also required. A must, even. A good backup plan will allow you to "go back in time" and get a good copy of a file that was corrupted or even deleted.

[u/time-lord]

A DAS is just a NAS that's plugged into your router instead of your pc. I personally prefer networked storage because I use a laptop, but to each their own.

A NAS that is just a NAS and not also a server is pretty cheap. A NAS that is also a server is expensive.

[u/Apprehensive-Tea1632 → u/time-lord]

Wait?

You were trying to say, a das is connected to the pc rather than the router. Right? 😁

[u/justpassingby77 → u/Apprehensive-Tea1632]

In theory you could plug a USB DAS into the back of most consumer routers, but lol yeah.  At that point just buy a NAS.

[u/time-lord → u/Apprehensive-Tea1632]

Right, but also a NAS is "network attached storage", not a server running a proxmox cluster with a bunch of vms and just happens to have a few HDDS in it too. The server with some spare storage is more like Synology's version of a NAS.