So I am thinking of buying two of these 8TB HDDs for archival purposes, putting them on an external USB stand that I have for 3.5" (and 2.5") SATA-drives.

https://www.gigantti.fi/product/tietokoneet/kiintolevyt-ssd-ja-verkkotallennus-nas/ST8000VN0022/seagate-ironwolf-3-5-sisainen-nas-kiintolevy-8-tb

(Two, because I am going to make them 1:1 identical copies of each other, so it is not like I need 16TB of total space for backups. 8 TB is fine, for now anyway. :))

1. The description says they are NAS-drives. What does that mean in practice? I am not going to use them in a NAS-setup but just connect them to my laptop through USB, are they fully suitable for that? Could they even be fully used as internal SATA HDDs on a desktop system, if needed? Meaning they have the performance what you'd expect from an internal HDD?

I mainly ask that because I recall in the past reading some user reviews for some bigger HDDs (>2TB) that they use some kind of data interleaving(?) method to increase the amount of data that can be fit into the HDD, but that also makes the HDD severely slow down in certain cases. Somehow I recall that might be a problem for me, e.g. if I'd try to uncompress and compress big files directly on those external HDDs (e.g. if I don't have enough room for those operations on internal hard drives, or just don't feel like copying files back and forth just for simple things like that).

Is that "data interleaving" still used, or an issue at all? Googling for it, I may have used the wrong term and it wasn't about interleaving, which apparently was some old method used on very old and early HDDs. I think I have asked about this before...

2. Do those very big HDDs (like 8TB) work fine on USB HDD stands, or are there some limitations I should know about? Currently I have 2x 3TB HDDs on such a stand, so should the 8TB HDDs work just as fine? I have this USB HDD stand:

https://www.verkkokauppa.com/fi/product/48273/dfdvn/Fuj-tech-Clone-Dock-USB-3-0-telakka-kahdelle-2-5-3-5-SATA-ki

Usually they are two drives internally in a 8~16 TB NAS.
You can use them as a whole, or use them separately (4 TB + 4 TB or 8 TB + 8 TB).

Google RAID if you need more information. As long as you have USB 3.x, everything will be fine.
USB 2.x also could be used, but the speed will be incredibly slow.

I use WD Mybook external hdisks for backup since 6 years.

I run Syncback free to update them every now and then.

Btw I don't use RAID, but instead I keep one of the disk offline, in case of ransomware..

The only drawback of these HDDs is that they're hardware encrypted, so if the controller dies, you won't be able to read your data via Sata..

Now you lost me. Are you saying that they are calling that 8TB hard drive "a NAS drive" because internally it is really two 4TB hard drives put together?

Even if they have crammed two 3.5" 4TB HDDs into that one internal 3.5" 8TB SATA HDD, why call it "NAS" when it is not accessed through the network, when you connect it directly to your SATA cable and use it as an internal hard drive?

I assumed they call it a "NAS-drive" because it is somehow considered more suitable for NAS-systems. The description also says "For 1-8 drives' NAS-solutions.". I was just trying to figure out what makes it "more suiitable" for NAS. Is it faster, or slower, or more reliable, or less reliable, than "normal" 3.5" SATA HDDs?

EDIT: Ok I think I found the answer from the NAS wikipedia page:

https://en.wikipedia.org/wiki/Network-attached_storage Unfortunately I have to use USB 2.0 for now as I have some long-standing issues with USB 3.0. Whenever I connect any external USB HDD directly to a USB 3.0 port and do some heavy file transfers or similar on it, the port suddenly dies or disconnects the hard drive. Sometimes within 10 seconds, sometimes after a few minutes etc. I have updated all the drivers on the system (with Slimware utilities), to no avail. I recall reading earlier that some USB 3.0 chipsets are faulty that way, so I guess I can't use USB 3.0 for heavy and long data transfers and file operations on this system.

If I connect those same USB HDDs to a USB 2.0 hard drive, or a powered USB 2.0 hub (which is connected to a USB 3.0 port), then they work fine without any issues. Yes they are slower, but a 100% reliability is a must when using USB HDDs. The USB 2.0 speed is fine for generic use and copying moderate amounts of data, but if I'd want to e.g. copy 3 TB of data from one USB 2.0 HDD to another, yes it certainly takes ages. Oh well, at least I can do something else with the PC while it is doing it in the background...

And no it is not about not enough power, as it happens also with USB hard drives which have their own power supply, not drawing the power through the USB. Yeah yeah, I've had a couple of external 2TB USB hard drives as well, one 3.5" one (with its own power supply) and another 2.5" one which gets its power from the USB port. Too bad my GOG game collection alone is already well past 2TB so they will not fit into one such hard drive.

I am buying normal (intermal) HDDs in this case, in order to use them on a separate USB HDD stand, for archival purposes. The stand-alone external USB HDDs are mainly if I'd need to move lots of data to some other physical place, like taking with me with my laptop and the laptop bag.

But NAS drives are ok for desktop use then?

At least that store didn't seem to have much of options with very big SATA HDDs (like over 4TB in size). They have a couple of different 4TB HDDs, one 6TB, and one 8TB. Since the 6TB and 8TB HDDs are the same price, I decided to go with the 8TB one. Both the 6TB and 8TB HDDs are called "NAS drives" in that store.

I am not going to buy 4TB HDDs as I already have two 3TB HDDs, so 4TB doesn't feel much of an upgrade over what I already have. I'll use the 3TB HDDs for some secondary backup stuff maybe, or connect them to my TV (with USB) in order to use them for recording TV programs/movies. No can do, I'm using laptops.

I asked about any potential limitations when using those very big HDDs on USB HDD stands because some of those stands state something like "supports max n TB hard drives". So I don't know if that means those USB stands will not work reliably with bigger HDDs than the supported ones, or that the vendor has only tested it with smaller HDDs.

Anyway, I think I sill order two such 8TB 3.5" SATA HDDs (for archival purposes), along with two or three 2TB 2.5" SATA HDDs (to be used as internal HDDs in my laptop, which currently has 2x 750GB HDDs which are already full). Time to get some serious storage space, and to hell with teeny-weeny SSDs.

You can get a DAS raid device and put several drives in. So long as you have a sepearte backup this is a good solution for security if a drive fails. I have one of these:
https://www.amazon.co.uk/TerraMaster-D5-300-External-Enclosure-Diskless/dp/B01KO03BBA/ref=mp_s_a_1_1?ie=UTF8&qid=1530617541&sr=8-1&pi=AC_SX236_SY340_QL65&keywords=terramaster&dpPl=1&dpID=41wgZJ9oeML&ref=plSrch

With 4,*4tb hdd's in raid 5. I also have and earlier version of that device with 3*6tb raid 5. Combine this with an internal seagate 10tb hdd. I use free file sync to sync up changes betweeen internal drive to these alternativng monthly, and each 6month-1year timepoint backup. Looking at anothe 10tb for this years timepoint backup.
I note the raid devices have gone up in price, mine was a fair bit lower than that price.

The performance is not optimal, but yes you can use NAS drives as Desktop drives.

If your laptop have high speed port like thunderbolt, you can buy an adapter to use USB 3.x.

As I thought, I used the wrong term in my first message (about some "trick" that some of these big HDDs may use to increase storage capacity, but may cause performance problems with bigger file operations).

The term was not "interleaving", but:

https://en.wikipedia.org/wiki/Shingled_magnetic_recording

And where I first learned about it was a 2015 user review for this cheapo 8TB SATA HDD:

https://www.verkkokauppa.com/fi/product/57150/fmdvq/Seagate-Archive-HDD-8-Tt-5900-rpm-3-5-SATA-III-6-Gt-s-kovale

The user warns there that since this HDD uses SMR (instead of the more commonly used PMR) to increase its storage capacity, the hard drive has serious performance issues when trying to write lots of data into it, as it needs to stop to "flush" data once in a while due to SMR. If you copy lots of data into it, like well over 50 GB (e.g. hundreds of gigabytes), it may slow down to a crawl, even mere 10MB/s. SMR apparently doesn't affect reading speeds, even with big amounts of data. Only writing is problematic.

So yeah, that's the term I must remember: NO SMR! I want only SMR-free HDDs from now on. Apparently the HDDs which are named as "NAS-drives" are a safe choice, they apparently never use SMR.

You learn something new every day, only to forget it the next day. I'm sure later I'll be again talking about "interleaving".

You mentioned multiple drives but didn't mention if you've tried different cables or are using the same one every time you hookup up a drive to your PC. I had a similar issue - 3.0 would sometimes work for a short while, drive would disappear, worked fine in USB2 - and I fixed it by swapping cables. If you've tried multiple cables, then hmmmm.....

Just wanted to add a good resource for general HDD reliability, the BackBlaze HDD stats blog:

https://www.backblaze.com/blog/hard-drive-stats-for-q1-2018/

What's the point?

You can get an external drive of same capacity (+ all cables and stuff) cheaper than buying an internal drive and some external stand for it.

https://www.gigantti.fi/product/tietokoneet/kiintolevyt-ssd-ja-verkkotallennus-nas/SGBUPHUBD8TB/seagate-backup-plus-hub-8-tb-ulkoinen-kiintolevy

In most cases you can, if you absolutely want to, tear the external casing apart, and what you find inside is actually an internal type of HDD that you can also use with a separate stand or something.

Yeah I've been long thinking of going to some kind of RAID setup, probably RAID5, as nowadays my space capacity is pretty much halved as I basically do 1:1 mirroring manually. Some clarifying questions about RAID(5) though:

1. Can the hard drives in a RAID setup be of different sizes, or do they have to be the same size? So e.g. if I already have two 3TB HDDs, could I just buy one or two extra 8TB HDDs and put all into a RAID5 setup, getting all the benefits? (I presume they'd have to be the same size, but just confirming...).

2. What happens in e.g. RAID5 if one small file gets corrupted on its own, without any file operation? Bitrot or whatever. Does the RAID5 setup notice and correct this automatically against the parity data, or will the corruption go through unnoticed?

I'm asking this because currently I fight the potential "bitrot" by doing a full rhash calculation and verification on both identical HDDs, just to see that nothing has become corrupted. If such would have happened on either HDD and I detect it with rhash, I just copy the uncorrupted file from the other HDD (I consider it a small possibility that the same file would become corrupted at the same time on both HDDs, so I always have a healthy file on either HDD, as long as I check the file integrity with rhash from time to time).

Yeah I currently do all this in a dumb manual way, but at least I am in control and know what I am doing and what is the status of my files (for the most part, anyway).

Good find, but I don't think that is the norm (ie. that an external USB HDD would be cheaper than a similarly sized internal HDD). Also I am unsure if that USB hard drive you mentioned uses that dreaded SMR that I mentioned earlier, and some cheaper big internal HDDs apparently use as well. Ie. the hard drive is ok for writing smaller amounts of data at a time, but not for big file operations because then the speed is severely reduced.

I already have a USB HDD stand (they cost only 30€ anyway) so I can swap internal HDDs into it freely, two at a time. So I can put e.g. two 8TB HDDs into it at the same time, using only one USB port.

In the past I've pried open a couple of my older USB HDDs when the controller or whatever on the casing has become broken and I've wanted to try to save whatever was on that hard drive. I started preferring internal HDDs with a separate casing or stand after I ran into a situation where a relatively new USB HDD stopped working, and I didn't know if the problem was with the casing, or the HDD itself. So I had to make a decision:

1. Return the broken external HDD to the store for a warranty refund, and lose any data in it in the process?

2. Pry the casing open and try to salvage any data from the hard drive inside, voiding the warranty at the same time? So if the problem was in the HDD itself anyway (ie. no data can be salvaged), I won't get any refund either because I have broken the casing?

By using separate casing/stand and internal HDD, I don't have that problem. If anything breaks, I can try to salvage the data, AND get the refund for the broken item.

Also, what phaolo said before, ie. if some integrated USB HDDs use hardware-level encryption, meaning the HDD can't be used without that casing? I wasn't aware or such though.

If you use an old USB HDD stand, its controller may not support very large HDD.
For example, one of my HDD dock only support 4 TB or smaller drives.