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Basic Questions About NAS

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EPAIII:
I am starting the process of purchasing a NAS system for my home network. As my home only has myself and my son, who has little interest in activities that use storage, this system will be primarily be used by myself for things like mechanical and electronic design (2D and 3D CAD), PCB creation, 3D printing, family photo storage, and video production. One of my greatest concerns is protecting the files from loss so redundancy is a must. And I do not wish to use cloud storage. I will be using two or even three different computers as well as an Android cell phone on this network (which includes Wifi). I hope that is a good description of the usage this NAS will be called on to support.

I am not a computer professional. So I must ask some basic questions that no one seems to discuss when describing these systems. I am thinking of using three drives in a RAID 1 configuration. That way, all of the data will be on each of the disks. If one goes bad, I still have redundancy (disks two and three) while ordering and installing a replacement drive. The first thing I want to know is can I (hot or not) swap a fourth drive into this RAID 1 and have it automatically become a fourth image of the other three? This assumes a four bay system or at least three. Then I could keep that fourth drive in a safe place, like a bank box, as an off site back-up, swapping it with one of the other three once a week or so. And if so, would this be a universal feature of any NAS? Or is it a question I should ask before buying?

A second, related question would be what I could do if the NAS itself goes bad, perhaps five or more years from now. The drives would have been set up/formatted by that NAS. Things in the computer world change rapidly. So there is no guarantee that that NAS or a compatible one would still be available. Even the company which made it could evaporate. So, could the individual drives be read by any computer? It seems to me that this is a very basic question that any NAS user should know the answer to.

I probably will have more questions, but those are the ones at the top of my mind at this point. Thanks in advance for any help on these questions.

Shonky:
RAID is not a backup....

What happens when you accidentally delete a file and it instantly replicates across all your 3 or 4 replicated disks? Or once your off site disk gets swapped in.

What happens if your house burns down? Or gets nearby lightning strike smoking your computers?

You won't use the cloud but are ok storing your almost live disk in a somewhat secured location?

Reconsider off site backup IMO. Easy enough to properly encrypt with your own keys etc.

sokoloff:
Based on experience with humans, I’d echo some of the concerns above. Things that need a human to remember and bother to do often don’t get done and surely don’t get done as reliably as an automated computer solution.

I started with an 8-bay Synology many years ago and have been very happy with it and often recommend that (or similar) course to others. You could also go with a 4 or 5 bay if that fit your needs better.

I’d do a minimum 4-disk SHR-2 with BtrFS and either have a cold spare drive sitting on your shelf or rely on Amazon to get me one in 2 days. I’d also create a shared volume for the most critical data that has snapshots and is automatically backed up off site somewhere (your own NAS at an office/other home, a friend/family member NAS, or cloud).

I’m designing to never lose critical files over multiple decades and protect against hardware failure but also user/application error, malware, and crypto lockers.

You can also create a less critical data shared volume that lacked off-site backup to save money on data that isn’t as critical.

Under the covers, Synology is using standard Linux block and file system software, so you could recover the data without Synology if you really had to.

This sounds like shilling for them, but I have no vested interest, just a long-time very happy user. The price isn’t the cheapest, but I bought mine 8 years ago and expect to use it at least another 5 years. (I’ve just recently cycled out the drives for larger and newer drives after about 7 years of power on time. It was a clear, easy, and slow [but unattended] process.) Even if it broke today, I’d be at a per-month price that I think is a good value.

ejeffrey:

--- Quote from: EPAIII on June 17, 2023, 09:22:30 am ---I am not a computer professional. So I must ask some basic questions that no one seems to discuss when describing these systems. I am thinking of using three drives in a RAID 1 configuration. That way, all of the data will be on each of the disks. If one goes bad, I still have redundancy (disks two and three) while ordering and installing a replacement drive. The first thing I want to know is can I (hot or not) swap a fourth drive into this RAID 1 and have it automatically become a fourth image of the other three?

--- End quote ---

All RAID systems support this, but the specifics of how to accomplish it depend on the device.  Dedicated RAID devices (like synology, qnap) will typically be configured to send you an alert when a drive fails, have an indicator to tell you which drive failed, and likely will have automatic or "single click" rebuild when you put a new drive in.  Purpose built RAID systems also almost always are designed for hot-swap.  The specifics would be in the manual.  If you went DIY, you would have to take care of all that yourself, and you might have to power down to do the swap.

Also, I think 3 drive RAID1 is probably not what you need.  In parity RAID (raid5, raid6) especially large arrays is really common to prefer double parity (raid6) to guard against drive failure during rebuild, but for a simple mirror setup (which by definition is small and relatively fast to rebuild), I think 2 drive failures are uncommon and the ones that do happen are often N drive failure caused by controller failure, power surge, getting unlucky with a HDD model that has a design flaw, theft, etc.  It's better to put that money into offsite backup.


--- Quote ---This assumes a four bay system or at least three. Then I could keep that fourth drive in a safe place, like a bank box, as an off site back-up, swapping it with one of the other three once a week or so. And if so, would this be a universal feature of any NAS? Or is it a question I should ask before buying?

--- End quote ---

Having a hot or cold spare is a good idea.  Rotating a "spare" in and out of the array as offsite backup is not really ideal it can work, but it is pretty limited:  First off, it's only a single backup, and your backup is invalid during the rebuild.  It's also "backing up" irrelevant data such as unused blocks.  Ideally you would like to design your backup around having 2 or more "full" backups and some number of "incremental" backups, such that when you go to reuse your oldest full backup, you still have a full backup and multiple incrementals.  For instance, you might do a full backup every 2 or 4 weeks, and incrementals nightly or a few times per week.  This gives you strong protection against hardware failure, user error, malware, and depending on how "offsite" you are talking, natural disaster.

You might not have enough network bandwidth to easily do a full backup even monthly.  In that case, you might just do on-site (but offline) backup, or use a cloud service that allows you only ever transmit incremental snapshots but maintains redundant full snapshots remotely.


--- Quote ---A second, related question would be what I could do if the NAS itself goes bad, perhaps five or more years from now. The drives would have been set up/formatted by that NAS. Things in the computer world change rapidly. So there is no guarantee that that NAS or a compatible one would still be available. Even the company which made it could evaporate. So, could the individual drives be read by any computer? It seems to me that this is a very basic question that any NAS user should know the answer to.

--- End quote ---

Most if not all consumer NAS on the market today are using relatively standard Linux or Free-BSD RAID tools.  You can likely plug them into a standard computer with a free operating system and get them to show up properly.  You would need to check on the particular system what OS, RAID, and filesystem format it uses.  A few systems used to use a proprietary format and would require you to purchase a replacement controller from the original manufacturer if you could find one, but I don't think that's common any more.

dobsonr741:
Based on what EPAIII said, EPAIII needs a backup, not necessarily a NAS. I would seriously reconsider a cloud backup option, as the NAS comes with serious ownership burden, if you really want to recover in case of data loss/theft/house burning down.

Consider the offsite backup, that the NAS would not be solving at all.

I would do a calculation, how much I would spend on building/maintaining/upgrading/testing/tinkering with the NAS, vs the benefit of a monthly or annual subscription fee, and doing more fun in the remainder of my lifespan the unburdening of the NAS maintenance would give back.

Oh, and privacy is not need to be harmed. It’s a right, just need to choose the right service and platform to buy.

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