Complete home server builds

Which of the three should you buy?

Answer one question honestly and the tier chooses itself: can you name the data that will fill it? Not the data you might collect one day, the data that exists now or that you already know you are about to create. Storage bought against a hypothetical is the most common expensive mistake in this category, because unused capacity earns nothing, still draws power every hour of every year, and ages on exactly the same schedule as capacity you are using.

If the answer is documents, a phone photograph library, a raw photography archive and backups of two or three computers, that is somewhere between 1 and 4 TB today and the $1,204 two-bay build gives you 8 TB of it with a drive of redundancy and a real second copy. You will not fill it quickly, and when you do, replacing both drives is straightforward.

If the answer includes a video library that grows every month, the two-bay tier is the wrong purchase and you will know it within a year. A 4K film library of 200 titles is 8 to 14 TB on its own. That is the case the $3,539 four-bay build exists for, at 24 TB usable with two drives of parity and the ability to grow drive by drive rather than all at once. This is where most readers should land.

The $7,890 eight-bay build is $4,351 more than the four-bay for four times the usable space. Per terabyte that is good value, at $82 against $147, and it is still $4,351 of real money. Buy it when you can point at the archives that need 96 TB, and not because the specification reads better.

Where the money actually goes

This is the single most useful table on the page, and it reorders how most people shop. Almost every buying guide in this category treats the enclosure as the decision and the drives as an afterthought. The arithmetic says the opposite.

Storage media is between two thirds and four fifths of every build here, and the share rises as the tier does. The enclosure never exceeds a quarter. Spending three weeks comparing two boxes that differ by $80, then buying whichever drives happen to be cheapest that week, gets the effort exactly backwards. The box is a one-time purchase that will still be running in five years. The drives are the recurring cost: they fail, they get replaced, and they get upgraded for as long as the server exists.

There is a practical consequence. If you are choosing between spending $200 more on an enclosure and $200 more on drives, the drives win almost every time, because capacity and redundancy are what you will actually run out of. The exception is Synology Hybrid RAID at the four-bay tier, which is a capability rather than a spec, and it is explained below.

What you actually get, after parity

Drive labels are decimal and operating systems are binary, so every capacity figure shrinks by a fixed 9.05 percent the moment the system reports it. Nothing is missing. On top of that, parity takes real capacity, and the filesystem takes a further one to two percent for metadata. The table below is what each build leaves you to fill.

Notice that the beginner build keeps half of what it buys and the expert build keeps three quarters. That is parity efficiency, and it is the honest argument for more bays: a mirror spends 50 percent of your drive budget on redundancy, while eight members with two drives of parity spend 25 percent. It is also the argument you should distrust most, because efficiency only pays if the capacity gets used, and the entry price to reach it is another $6,686.

Run your own drive set through the RAID capacity calculator before you commit. It handles mixed drive sizes, shows how much capacity a standard array strands when the members are not identical, and covers every layout these three builds can run. The reference charts carry the unit conversion at every capacity if the reported figure is what is confusing you.

What each tier protects you against, and what it does not

All three builds survive a drive failure. The intermediate and expert builds survive two, which matters more than it sounds like it should, because the dangerous window is not the failure itself but the rebuild that follows it.

Reconstructing a failed member means reading every surviving drive from end to end. On the four-bay build that is roughly 36 TB of reads over about a day. On an eight-bay array under single parity it would be 112 TB of reads over nine to fourteen days, on drives that are the same age, from the same batch, and have done the same work as the one that just died. Under single parity you have no redundancy at all for that entire window. That is why the expert build runs RAID 6 rather than RAID 5, and why the four-bay build leans toward SHR-2. The drive failure probability calculator puts numbers on it for your own drive count and age.

What none of the three protects against is everything that reaches the whole chassis at once: deleting a folder and emptying the bin, ransomware encrypting a mounted share, a controller writing corruption to every member, theft, fire, flood. Parity is indifferent to all of it, because it faithfully protects whatever the array was told to store. That is why every build here carries an external backup target as a required line and not an upgrade.

The array is copy one, not the backup. If a budget will not stretch to the whole list, drop to smaller drives rather than dropping the second copy. A 4 TB mirror with a backup is a finished server. An 8 TB mirror without one is a single point of failure that happens to contain two drives.

The backup problem gets harder as you go up

This is the part most build guides quietly skip, and it is worth stating plainly. At the beginner tier a single $274.23 external drive covers the entire 8 TB array with room to spare. At the intermediate tier a $700.35 drive covers your used data comfortably for the first several years of a 24 TB volume, which is realistic but no longer automatic.

At the expert tier the arithmetic breaks. Two 20 TB externals are 40 TB against a 96 TB array, and no consumer approach closes that gap affordably. The correct answer at that scale is tiered rather than complete: fully back up the irreplaceable data, which is usually 5 to 20 TB of photographs, documents and original work, and accept that re-downloadable media is protected by parity alone. That is a defensible position. Claiming a 96 TB array is fully backed up by two external drives is not. Size your tiers against the data you actually use rather than against raw capacity, and see the guides section for how the copies should be distributed across locations.

What it costs to leave running

A server runs 8,760 hours a year, so idle power is a real line in the total cost of ownership rather than a footnote. Two spinning drives plus a small x86 board sit around 30 to 38 W at idle. Four drives and a larger board sit around 45 to 60 W. Eight drives and a ten-core processor sit around 85 to 120 W.

At a tariff of 17 cents per kWh, using watts divided by 1,000, multiplied by 8,760, multiplied by the tariff, that is roughly $45 to $57 a year for the beginner build, $67 to $89 for the intermediate and $127 to $179 for the expert. Over five years the electricity on the beginner build costs more than its enclosure did, and on the expert build it approaches the price of another drive. Put your own tariff and hardware into the power draw calculator, and size the battery with the UPS runtime calculator, remembering that VA is not watts: consumer units publish a power factor around 0.6 to 0.9, so a 650 VA unit delivers roughly 390 W.

Upgrading later, and when to jump a tier instead

Every tier can grow, but the cost of growing differs enough to change which one you should buy today. On the two-bay mirror, more capacity means replacing both drives at once, so the upgrade is a single lump and the old drives leave the array together. That is simple and it is not cheap.

On a four-bay running standard RAID 5 or RAID 6, replacing two of four drives with larger ones gains you exactly nothing until every member is upgraded, because standard RAID truncates every drive to the size of the smallest one. Synology Hybrid RAID is the one consumer scheme that escapes this and uses the extra capacity as you add it. That single capability is the whole argument for paying Synology prices at the four-bay tier, and it is worth it only if you genuinely intend to grow drive by drive. Put a mismatched drive set into the RAID capacity calculator to see exactly how much capacity a standard array strands and Synology Hybrid RAID keeps.

The signal to jump a tier rather than upgrade in place is the 80 percent mark. When a volume is genuinely 80 percent full and still growing, the money spent on larger drives for the current chassis usually buys a better outcome in the next chassis, with the old box demoted to a backup target. That is a much better second life than selling it, and it turns the upgrade into an extra copy rather than a replacement.

The order to add things in, at every tier, is the same: network first, because a 2.5 gigabit switch is the cheapest visible improvement in home storage, then a third copy kept somewhere other than your house, then capacity. Faster hardware comes last, and usually never. Each of the three build pages works through that order for its own tier.

What every build here has in common

Three requirements are fixed across all three tiers, and they are the reason these lists look more expensive than the ones that end at an enclosure and some drives.

CMR recording, never SMR. Shingled drives overlap tracks like roof tiles to raise density, which means rewriting a sector can require rewriting its neighbours. Under the sustained random writes of a rebuild, an SMR drive can slow to a crawl and stretch a rebuild from a day into several, during which the array has no redundancy. Every drive in every build here is CMR. The NAS hard drive guide covers how to check the recording method on a specific model before you order it.

A published workload rating. NAS drives publish a rating in terabytes written and read per year, typically 180 TB for consumer NAS tiers and 300 to 550 TB for Pro and enterprise. A desktop drive with no published rating was not designed to spin continuously, and its warranty frequently says as much.

A UPS on every tier, including the cheapest. Its job is not to keep you working through an outage. It is to give the server enough warning and enough seconds to close its writes and shut down cleanly, which is precisely the failure mode parity cannot cover. It is the item people skip most often and the one that protects against the fault RAID was never designed for.

Compare the parts individually

• Best NAS hard drives, where most of every budget on this page goes
• Best budget NAS, the two-bay alternatives
• Best NAS for home, the four-bay field
• Best 8-bay NAS, the expert tier compared
• Best NAS for Plex, if transcoding is the reason you are buying
• RAID capacity calculator, for any drive set including mixed sizes
• NAS model specifications, with usable capacity computed for every layout