Almost every used-server guide helps you choose a model. Almost none helps you choose the configuration, which is the decision that actually determines what the machine can hold - and unlike the model, it is not something you can change afterwards. On this class of hardware the backplane is fixed at point of purchase.
Prices updated
| 12-bay LFF | 24-bay SFF | |
|---|---|---|
| Typical bay count | 12 | 24 |
| Carrier size | 3.5" LFF | 2.5" SFF |
| Cheapest $/TB, live | $14.00 | $33.33 |
| Largest drive we stock | 14 TB | 3.84 TB |
| Carrier, per unit | $6.80 | $5.10 |
| Carriers to fill | 12 × = $82 | 24 × = $122 |
| Drives in stock | 20 | 16 |
Prices are live from our catalogue. Where a chassis shows a band rather than a figure, we hold no verified Amazon listing for it and the range is a dated estimate rather than a quote.
The table above is drawn from our live catalogue and it is the single most useful thing on this page. Large-format drives are cheaper per terabyte than small-format ones, and it is not a marginal difference - it is the difference between a bulk array being affordable and not.
The reason is physical rather than commercial. A 3.5-inch drive has room for more platters of greater diameter, so the highest capacities are only manufactured in that form factor. The 2.5-inch market tops out far lower for spinning disks, and the high-capacity end of it is enterprise SSD, which is a different price bracket entirely.
So twelve large bays will generally hold considerably more usable capacity than twenty-four small ones, for considerably less money, despite having half the bay count. Bay count is the number people compare, and it is the wrong number.
A twenty-four bay chassis needs twenty-four carriers to fill. A twelve-bay chassis needs twelve. Carriers are inexpensive individually and meaningful in quantity, and the small-format ones are not cheaper per unit - our live per-caddy figures are on the carrier pages and the difference between filling one chassis and the other is real money that rarely appears in anybody's budget.
Multi-packs mitigate this and are the sensible way to buy, which is why our carrier tables rank on price per caddy rather than pack price. But the arithmetic does not go away: twice the bays is twice the carriers.
This is the part that matters most, because the backplane is chosen when the machine is built and is generally not a field upgrade. You are not picking today's storage; you are picking the ceiling for the life of the machine.
A large-format chassis commits you to spinning disks in the main. You can put a 2.5-inch drive in a 3.5-inch carrier with an adapter bracket, so SSDs are not excluded, but you are carrying twelve bays of infrastructure to hold drives that would fit in a smaller machine. It is the right choice for bulk capacity and the wrong one for a machine that will end up all-flash.
A small-format chassis commits you the other way. Spinning disks in 2.5-inch are limited in capacity and poor value per terabyte, so the sensible use of a 24-bay SFF machine is enterprise SSDs - and on the platforms that document it, U.2 NVMe. That is a genuinely good machine for a virtualisation host or a database, and a genuinely poor one for a media library.
The mistake to avoid is buying twenty-four small bays because twenty-four sounds better than twelve, and then discovering that filling them with capacity costs several times what the large-format machine would have.
If the build is all-flash, the calculus inverts. Enterprise SSDs are overwhelmingly a 2.5-inch market, the capacity ceiling per drive is high, and twenty-four bays of flash is a serious machine. Several of the platforms we cover document NVMe support only on their small-format configurations - the R730xd's four Express Flash drives, the R640's eight, the DL380 Gen10's much larger allowance - so if NVMe in hot-swap bays is the plan, the small-format chassis is not merely preferable, it is the only option.
The hybrid pattern is worth knowing too: a handful of small-format bays for fast storage and a large-format chassis for bulk. Some platforms support this directly through rear or mid-plane cages, which our per-model pages document where the vendor states them.
Whichever way this comparison goes, it is worth keeping the numbers in proportion. The gap between these two options is usually a couple of hundred dollars. Filling the machine with drives is usually several times that, and it is the same purchase either way.
That has a practical consequence for how you should weigh this decision. Agonising over the chassis while the drives dominate the budget is optimising the smaller line — and if the cheaper option leaves enough headroom for one more drive, that extra drive will change how the finished machine feels far more than the platform generation will. The exception is a build that is genuinely compute-bound rather than storage-bound, where the platform is the thing you are buying and the drives are incidental.
The other thing worth pricing before you commit is what the machine needs beyond the chassis: a carrier for every drive, and a storage controller that suits your filesystem. Neither is expensive individually and together they routinely add more than the price difference this page is about. Our build calculator prices the whole list for either option so you can compare finished machines rather than bare chassis, which is the comparison that actually matters.
On condition: recertified enterprise drives are the normal supply for builds like these and usually the right buy — the same drives at a fraction of the price, typically rated for a higher duty cycle than the consumer drives they undercut. What you trade is warranty length and inherited powered-on hours. The table below shows condition alongside price so the comparison stays honest rather than floating used drives to the top as though they were equivalent to new ones. For a parity array, check the recording technology as well — no parity level rescues an array built on shingled drives.
8 in-stock listings · conventionally recorded, 3.5in, ranked by cost per terabyte · ranked by live cost per tb, refreshed every few hours
| Drive | Capacity | Interface | Recording | Condition | $/TB | Price | |
|---|---|---|---|---|---|---|---|
| HP 695842-001 4TB SAS 6G 695842-001 | 4TB | SAS-6G | CMR | NEW | $14.00 | $56 | Buy |
| HP ST31000640SS 1TB SAS ST31000640SS | 1TB | SAS-6G | CMR | REFURB | $14.99 | $15 | Buy |
| HGST HUS724030ALS640 3TB SAS 6G HUS724030ALS640 | 3TB | SAS-6G | CMR | REFURB | $15.13 | $45 | Buy |
| Seagate 3TB Enterprise Capacity SAS 6G ST3000NM0023 | 3TB | SAS-6G | CMR | REFURB | $17.98 | $54 | Buy |
| HGST HUS726040ALS210 4TB SAS 12G HUS726040ALS210 | 4TB | SAS-12G | CMR | REFURB | $18.13 | $73 | Buy |
| Dell NWCCG 6TB SAS 6G NL Renewed NWCCG | 6TB | SAS-6G | CMR | REFURB | $18.33 | $110 | Buy |
| MDD 6TB SAS 12G 7200RPM MD6TSAS12872E | 6TB | SAS-12G | CMR | REFURB | $18.33 | $110 | Buy |
| HP 695842-001 4TB SAS 6G LFF 695842-001 | 4TB | SAS-6G | CMR | NEW | $19.67 | $79 | Buy |
Complete build guides · Price your own configuration · Where to buy
Other comparisons: PowerEdge R730 vs PowerEdge R740 · ProLiant DL380 Gen9 vs ProLiant DL380 Gen10 · PowerEdge R630 vs PowerEdge R730
For bulk capacity the large-format configuration wins and it is not close. Our live catalogue currently shows the cheapest 3.5-inch drive at $14.00 per terabyte against $33.33 for 2.5-inch. Twelve large bays hold more usable capacity for less money than twenty-four small ones, despite half the bay count — because the highest-capacity drives are only manufactured in 3.5-inch. The small-format chassis wins when the build is all-flash or needs NVMe in hot-swap bays.
No, and this is the crux of the decision. A 3.5-inch bay takes a 3.5-inch drive; a 2.5-inch bay takes a 2.5-inch drive. You can put a small drive into a large carrier with an adapter bracket, but you cannot make a large drive smaller. Since the highest capacities are only made in 3.5-inch, the configuration you buy sets a ceiling on what the machine can ever hold — and the backplane is fixed at point of purchase.
There is no newer one here — this is a configuration choice within the same machines, which is exactly why it gets so little coverage and matters so much. The question is not age but shape: what you can put in the front of the chassis for the life of the machine.
We publish no decibel figures for any machine on this site, because we have not measured any and vendors do not state them for used configurations. What is consistent in owner reports is that 1U chassis are louder than 2U ones of the same era — small fans move air by spinning faster — and that hardware the management controller does not recognise raises the fan floor on all of them. That is community reporting and we label it as such. Our noise page covers the landscape and the mitigation options honestly.
The tiering model is the same across generations and vendors: the virtual console with virtual media, which is the feature that makes a machine administrable from elsewhere, sits behind the licensed tier rather than the free one. What varies is the interface generation. The buying advice does not change — ask the seller which tier is active on the specific machine, in writing, because it does not appear in a listing photograph.
Bay and backplane data comes from the vendors' own documentation — Dell technical guides and owner's manuals, HPE QuickSpecs, Lenovo setup guides — cited on each model's page. Prices come from our live catalogue and refresh every few hours. Anything drawn from community reporting rather than a vendor document is labelled as such, including the fan-behaviour observations, because a forum consensus and a specification are different kinds of claim.