Sabrent rates the offline clone on its EC-HD2B dock at 60 MB/s. At that rate a sector-by-sector copy of a 20TB drive runs for about 93 hours. The StarTech SDOCK2U313R is rated at 28 GB/min, so the drive becomes the limit. It is also the only one of the five hard drive docking stations here with a 10 Gbps host link. For a batch of Black Friday drives, those two figures decide more of your week than a $20 price gap or a fourth bay.
Each HDD docking station below is ranked by clone rating and host link speed. We read the Linux side against the smartmontools USB tables and the kernel UAS quirk list. Specs come from the maker pages, drive arithmetic from the Seagate IronWolf Pro datasheet, and prices from the Amazon catalog (checked October 2026, $30 to $100). Our best drives to shuck guide covers the disks.
Hard drive docking stations ranked by clone and link speed
Only one dock in this group is rated past 5 Gbps, and only three state a clone speed at all. The table carries the figures each maker publishes, so a blank in it means the maker states nothing, not that we rounded it away:
| Dock | Bays | Host link | Offline clone (maker rating) | Max drive (maker) | Approx. price |
|---|---|---|---|---|---|
| StarTech SDOCK2U313R | 2 | USB 3.2 Gen 2, 10 Gbps, USB-C and USB-A cables | Up to 28 GB/min, target equal or larger | Any capacity, 4Kn supported | about $100 |
| Sabrent EC-HD2B | 2 | USB 3.0, 5 Gbps, USB-B | Up to 60 MB/s | 20TB | about $45 |
| Sabrent EC-CH2B | 2 | USB 3.0, 5 Gbps, USB-C connector | Up to 60 MB/s | 20TB and more | about $47 |
| Sabrent DS-U3B4 | 4 | USB 3.0, 5 Gbps shared, SATA 3 Gb/s per drive | Not on the maker page | Not stated | about $100 |
| Sabrent EC-DFLT | 1 | USB 3.0 | None | 20TB | about $30 |
Read the clone column against your drive size. At 60 MB/s the two Sabrent cloners need 74 hours for a 16TB disk and 93 hours for a 20TB one. A sector copy reads every block whether it holds data or not (the Sabrent FAQ says an empty source takes as long as a full one). The StarTech rating works out to about 467 MB/s. That is well above the 285 MB/s Seagate lists as the outer-track peak of a 20TB IronWolf Pro, so on that dock the drive sets the pace:
- Fastest standalone clone: StarTech SDOCK2U313R, the only 10 Gbps dock here and the only clone rating a hard drive cannot saturate.
- Best value dual bay: Sabrent EC-HD2B, two drives on one USB-B cable plus a 60 MB/s offline clone for about $45.
- Same dock, USB-C cable: Sabrent EC-CH2B, identical 5 Gbps link and clone rating, only the connector differs.
- Most drives at once: Sabrent DS-U3B4, four bays behind one 5 Gbps link, which matters for week-long burn-in runs.
- Cheapest single bay: Sabrent EC-DFLT, one drive and a power switch for about $30.
None of these is a NAS enclosure. A dock is for drives that come and go: a first surface scan, a shucked white label, a clone before a swap. For drives that stay attached around the clock, a DAS or JBOD enclosure with proper cooling is the better buy.
How the docks were compared
Every spec column in the table traces to the product page of its maker, which we read on 31 October 2026; usage details come from the Sabrent forum and owner reviews, and the text names them. Each pick also has an entry in our sourcing log. Where Amazon listing copy and the maker disagree, the maker wins. The clearest case is the DS-U3B4. Its Amazon title says “Clone”, but the Sabrent product page never mentions cloning, so we do not count it as a cloner.
Hours in this guide are arithmetic, not stopwatch readings. They divide drive capacity by the clone rating or by the 285 MB/s outer-track figure on the Seagate IronWolf Pro 20TB datasheet (DS1914). Inner tracks run slower than the outer edge, so every hour figure built on 285 MB/s is a floor. We dropped a sixth candidate, a UGREEN dual-bay cloner. UGREEN publishes no product page for it, and its Amazon listing gives three different maximum capacities.
1. StarTech SDOCK2U313R: fastest standalone duplicator
StarTech rates the SDOCK2U313R at up to 28 GB/min for standalone sector-by-sector duplication. The host side is USB 3.2 Gen 2 at 10 Gbps, with USB-C and USB-A cables in the box. The product page also lists SATA III per bay, TRIM, 4Kn drives and no capacity limit. The target drive must be equal to or larger than the source.
That 28 GB/min is about 467 MB/s, which no 3.5-inch hard drive sustains. A 20TB IronWolf Pro peaks at 285 MB/s on its outer tracks. A full clone of one therefore takes at least 19.5 hours here, against about 93 hours on the Sabrent cloners. On a 16TB drive the floor is 15.6 hours. The headroom matters more for SATA SSDs, and for the 10 Gbps host link when both bays are mounted on a Linux box at once.
Who it is for: anyone who clones 16TB and larger disks, where the difference is three days per copy. Skip it if you only need to read one drive at a time, because the about $100 price buys speed a single scan cannot use. StarTech backs it with a 2-year warranty and lifetime technical support. Check the live price on Amazon.
2. Sabrent EC-HD2B: best value dual-bay dock with offline clone
The EC-HD2B takes two 2.5-inch or 3.5-inch SATA drives up to 20TB each over a 5 Gbps USB 3.0 link. The Sabrent FAQ confirms both bays are visible to the host at the same time. Its offline clone is rated up to 60 MB/s and runs with the USB cable unplugged, as Sabrent support staff tell owners on the maker forum.
As a two-drive reader the EC-HD2B does the job for about $45, and you can scan a pair of new disks inside the return window. As a cloner it is slow. A 60 MB/s copy of a 12TB drive takes about 56 hours, and the clock runs the same for an empty disk as for a full one. For drives under 4TB (about 19 hours) that is acceptable. For a part-full 20TB disk, imaging it with Clonezilla over USB copies only used blocks and finishes sooner.
It suits a homelab bench that reads, wipes and now and then duplicates small to mid-size drives. Look elsewhere when a clone of a 16TB or larger disk is the reason for buying a dock. Sabrent lists no Linux support on the page and names no bridge chip, and the 2-year warranty requires registration within 90 days. Check the live price on Amazon.
3. Sabrent EC-CH2B: the same 5 Gbps dock with a USB-C port
The Sabrent EC-CH2B swaps the USB-B socket for USB-C and is pictured with a USB-C to USB-C cable. Its product page still says transfer speeds up to 5 Gbps with USB 3.0. The USB-C port changes the cable, not the throughput. Bay count, the 60 MB/s offline clone and the “20TB and more” drive support match the EC-HD2B.
Two owner reviews on the Sabrent product page are worth reading before you buy. One reports that unRAID showed the two bays with distinct drive identifiers, which is what you want when both disks sit on the same host. Another reports that the offline clone stalled on a source drive with bad sectors instead of skipping them. A sector cloner cannot work around a dying disk. A failing source belongs on a tool that retries and logs bad blocks, not on a dock button.
Buy it for a laptop or mini PC with only USB-C ports, where a native cable beats an adapter. With a free USB-A port on the host, the EC-HD2B does the same work for slightly less. The page lists Windows and macOS only, which says nothing about Linux either way: USB mass storage needs no vendor driver. Check the live price on Amazon.
4. Sabrent DS-U3B4: four drives burning in at once
The DS-U3B4 holds four 2.5-inch or 3.5-inch drives behind a single 5 Gbps USB 3.0 link, with each bay at SATA 3 Gb/s according to Sabrent. That per-bay figure is about 300 MB/s of payload, above what a hard drive sustains. The shared USB link is the real limit once more than one bay is busy.
USB 3.0 at 5 Gbps uses 8b/10b line encoding, which leaves about 500 MB/s before protocol overhead. Four drives that could each stream 285 MB/s therefore get at most 125 MB/s apiece when all four run together. A four-pattern destructive burn-in writes each pattern to every block and reads it back, eight full passes, so a single 20TB drive needs at least 6.5 days at full speed. Four of them in this dock need at least 14.8 days in parallel, against 26 days if you ran them one after another on a single-bay dock.
Who it is for: a batch of four new or recertified drives that all need a surface scan before the return window closes. Pass on it for cloning, since the Sabrent page lists no clone function despite the word in the Amazon title. Two dual-bay docks on separate USB controllers finish the same four-drive burn-in in about 7.4 days for a similar price. Check the live price on Amazon.
5. Sabrent EC-DFLT: single-bay dock for checking one shucked drive
The EC-DFLT is a hot-swappable single bay for one SATA drive up to 20TB over USB 3.0. It has an on/off power switch and no clone function. At about $30 it is the cheapest way to read the model string of a drive you just pulled from a WD or Seagate external, though SMART access depends on a bridge chip Sabrent does not name.
A switch on the dock means you can power a drive off without pulling cables, which helps on a bench where disks swap all day. Its real limit is the single bay. Copying between two disks means a second dock or a SATA port inside a PC.
The EC-DFLT fits someone shucking one or two drives a year who wants to confirm the disk inside before the case goes in the bin. Batch testers should pass, because one bay turns a four-drive burn-in into a month. The Sabrent warranty is 2 years with registration. Check the live price on Amazon.
What the USB bridge chip decides on Linux
Inside every dock is a USB to SATA bridge. On Linux that chip decides whether you can read SMART data and whether the kernel uses the faster UAS driver. None of the five makers names its bridge, so judge these points after the dock arrives, while it can still go back:
- SMART passthrough: the smartmontools USB page lists SAT pass-through for ASMedia, Initio, Oxford and newer JMicron bridges, and its device table shows some firmware returning incomplete SMART status. A dock that hides SMART is useless for vetting a shucked or recertified drive.
- UAS quirks: the kernel file unusual_uas.h keeps UAS on for JMicron JMS567 bridges with a broken-FUA flag, and disables it only for a JMS566 under vendor ID 357d. JMicron bridges report vendor ID 152d and ASMedia 174c in the kernel log.
- Two separate disks: a dual-bay dock should present each bay as its own drive with its own serial number. The smartmontools table lists a dual dock as DISK1 and DISK2, and the EC-CH2B review above reports the same in unRAID.
- The 3.3 V pin: none of the five makers states whether its SATA power feeds 3.3 V. A shucked white-label drive that never spins up in a dock is the classic power-disable symptom, and the shucking guide covers the pin.
Offline clones carry two Linux traps that no maker page mentions. A sector copy duplicates the partition table and every filesystem UUID. Mount the source and the clone on one host and you get two disks with identical IDs, which confuses mounts by UUID, LVM and Btrfs. Cloning onto a larger target leaves the backup GPT header where the source ended, mid-disk. Partitioning tools report the table as damaged until it moves to the real end. The same bridge rules apply to NVMe enclosures, where TRIM over USB adds a third, as the NVMe enclosure guide explains.
How long a 20TB clone and burn-in take per dock
Every row divides 20TB by the clone rating or by the 285 MB/s IronWolf Pro peak, whichever is lower. Treat the hours as the fastest a dock can finish. Burn-in assumes eight full passes per drive, the write-and-verify cycle of a four-pattern destructive scan:
| Dock | Offline clone, 20TB | Burn-in, one 20TB drive | Burn-in, four 20TB drives |
|---|---|---|---|
| StarTech SDOCK2U313R | at least 19.5 h (drive-limited) | at least 6.5 days | at least 13 days, two at a time |
| Sabrent EC-HD2B | about 93 h (60 MB/s rating) | at least 6.5 days | at least 14.8 days, two at a time on a shared 5 Gbps link |
| Sabrent EC-CH2B | about 93 h (60 MB/s rating) | at least 6.5 days | at least 14.8 days, two at a time on a shared 5 Gbps link |
| Sabrent DS-U3B4 | No clone on maker page | at least 6.5 days | at least 14.8 days, all four on a shared 5 Gbps link |
| Sabrent EC-DFLT | No clone | at least 6.5 days | at least 26 days, one at a time |
Two results stand out. On a four-drive batch every 5 Gbps dock needs at least 14.8 days. Two drives sharing that link get 250 MB/s each and need two rounds, while four get 125 MB/s in one round. Only the 10 Gbps StarTech, or two docks on separate USB controllers, gets below that. The second is that the clone rating, not the link, separates the StarTech from the Sabrent cloners: 19.5 hours against 93. For the drives themselves, the NAS hard drive guide ranks the CMR models these docks will spend most of their time scanning.
