The title says basically everything but let me elaborate.
Given the recent news about the sold out of harddrives for the current year and possibly also the next years (tomshardware article) I try to buy the HDDs I want to use for the next few years earlier than expected.
I am on a really tight budget so I really don’t want to overspend. I have an old tower PC laying around which I would like to turn into a DIY NAS probably with TrueNAS Scale.
I don’t expect high loads, it will only be 1-2 users with medium writing and reading.
In this article from howtogeek the author talks about the differences and I get it, but a lot of the people commenting seem to be in a similar position as I am. Not really a lot of read-write load, only a few users, and many argue computing HDDs are fine for this use case.
Possibilites I came up with until now:
- Buy two pricey Seagate Ironwolf or WD Red HDDs and put them in RAID1
- Buy three cheaper Seagate Barracuda or WD Blue and put two in RAID1 and keep one as a backup if (or should I say when?) one of the used drives fails.
I am thankful for every comment or experience you might have with this topic!
First and most important:
In the context of long-term data storage
ALL DRIVES ARE CONSUMABLES
I can’t emphasize this enough. If you only skim the rest of my post, re-read the above line and accept it as fundamental truth. “Long-term” means 1+ years, by the way.
It does not matter what type of drive you buy, how much you spend on it, who manufactured it, etc. The drive will fail at some point, probably when you’re least prepared for it. You need to plan around that. You need to plan for the drive being completely useless and the data on it unrecoverable post-failure. Wasting time and money to acquire the fanciest most bulletproof drives on the market is a pointless resource pit, and has more to do with dick-measuring contests between data-hoarders.
Knife geeks buy $500+ patterned steel chef’s knives with ebony handles and finely ground edges and bla bla bla. Professional kitchens buy the basic Victorinox with the plastic handle. Why? Because they actually use it, not mount it on a wall to look pretty.
The knife is a consumable, not an heirloom. So are your storage drives. We call them “spinning rust” for a reason.
The solution to drive failure is redundancy. Period.
Unfortunately, this reality runs counter to the desire to maximize available storage. Do not follow the path of desire, that way lies data loss and outer darkness. Fault-tolerant is your watchword. Component failure is unpredictable, no matter how much money you spend. A random manufacturing defect will ruin your day when you least expect it.
A minimum safe layout is to have 2 live copies of data (one active, one mirror), hot standby for 1 copy (immediate swap-in when the active or mirror fails), and cold standby on the shelf to replace the hot standby when it enters service.
Note that this does not describe a specific number of disks, but copies of data. The minimum to implement this is 4 disks of identical storage capacity (2 live, 1 hot standby, 1 on the shelf) and a server with slots for 3 disks. If your storage needs expand beyond the capacity of 1 disk, then you need to scale up by the same ratio. A disk is indivisible - having two copies of the same data on a disk does not give you any redundancy value. (I won’t get into striping and mucking about with weird RAID choices in this post because it’s too long already, but basically it’s not worth it - the KISS principle applies, especially in small configurations)
This means you only get to use 25% of the storage capacity that you buy. Them’s the breaks. Anything less and you’re not taking your data longevity seriously, you might as well just get a consumer-grade external drive and call it a day.
Buy 4 disks, it doesn’t matter what they are or how much they cost (though if you’re buying used make sure you get a SMART report from the seller and you understand what it means) but keep in mind that your storage capacity is just 1 of the disks. And buy a server that can keep 3 of them online and automatically swap in the standby when one of the disks fails. Spend more money on the server than the disks, it will last longer.
Remember, long-term is a question of when, not if.
I enjoyed the depth of this answer. That being said…
4 copies seems like a level of paranoia that is not practical for the average consumer.
3 is what I use, and I consider that an already more advanced use case.
2 is probably most practical for the average person.
Why do I say this? The cost of the backup solution needs to be less than the value of the data itself x the effort to recover the incrementally missing data x the value of your time x the chance of failure.
In my experience, very few people have data that is so valuable that they need such a very thorough backup solution. Honestly, a 2$ thumb drive can contain most of the data the average user would actually miss and can’t easily find again scouring online.