A few months ago I purchased an OWC dual drive bay USB-3 (3.1 gen. 2) dock for making off-site backups (this is in addition to automated Time Machine backups on a dedicated hard drive just for that) to standard SATA hard drives/SSDs and I thought I'd share my experiences with others interested (Note: this isn't an accurate scientific test but more from a practical user-perspective).
I'm using it with a mid-2010 Mac Pro running MacOS 10.13.6 High Sierra, and it's attached via a USB-C/USB-C cable to a Sonnet Allegro USB-3C-4PM-E (four 10 Gbps USB-C ports, dual controller chip) PCIe card. I haven't done any proper speed tests or anything, but from a user perspective it appears to back up just as fast as I did before with my Firewire-800 setup (more below) -I'm guessing faster as well had I done a speed test.
(image source: OWC)
(image source: OWC)
OK, last thing first (I know you're wondering): yes, I'm super happy with this drive dock!
Now on with the details....
Why I need this drive dock
To start off I have to add that I already had a fully working removable backup solution which I've used for many years already: a 4-bay 1U 19" rack-mounted Proavio Studiorack S4 connected via Firewire 800 to my mid-2010 Mac Pro. It allowed me to make external backups and backup archives (i.e. additional backups to keep in a physically different place than the usual backups in case of theft, fire, floods etc.) and has served me well for many years.
I've used Chronosync for this (and still am, now with the new drive dock) which I've found very good for doing backups other than Time Machine. It took me a little while to understand, but thanks to excellent support, great guides on their website and regular updates with improvements it's become a solid piece of software which I use all the time. Actually, once set up I don't have to think about it because everything happens automatically. I can now insert a backup drive in the dock and Chronosync starts up automatically and performs the backup. And it does this for all my different backup drives, so I really don't have to do much more than insert the drive(s) in the dock, power them on, then when everything's done I eject, power down the dock bay(s) and remove the drive(s).
There are other backup tools around, but I decided to give Chronosync a go when I first looked into doing backups (beyond Time Machine) and I haven't looked back since. I highly recommend it!
(image source: BHphotovideo.com)
But back to the hardware... this setup worked well for years, but as my storage needs have grown I've outgrown that rack solution because it only takes 2 TB or 3 TB (I forget which) drives or smaller. This has resulted in many physical drives laying around which means more physical space needed and more hassle finding and inserting/removing drives whenver I need to backup.
And any new drives need to be mounted (with screws) in a new drive sled, so I had to buy a bunch of those as well. Firewire 800 was fine for me (as the Mac Pro has those ports) but newer computers don't, so it was time to look for something else....
The OWC dual drive dock ticks off just about all my boxes and more! Read on....
Two drive bays
Yes, it "only" has room for two SATA drives (not four as with my Proavio Studiorack) but actually I seldom need to access 4 drives at once. Without any sleds to mount it's so easy to just insert/remove a bare drive, so it's no problem exchange drives quickly, and you don't need to buy expensive and sometimes hard to find sleds for a particular type of dock. And since newer high capacity drives have a different screw mounting layout than all previous drives (i.e. the screw holes no longer match that of older drives) because of the larger platters inside you'd be getting problems if newer sleds aren't available or the ones you have cater for all SATA drives (for my Mac Pro I had to buy new drive sleds (also from OWC by the way) in order to remedy this. Not so when using high capacity hard drives with this dock -there simply isn't any permanent mounting of the drives to be done. Simply press the bare drive into its SATA connectors to attach it, and likewise to remove it you carefully pull the drive upwards. Each bay is covered by a spring-loaded "door" by the way, which is a nice touch to keep dust away from its SATA connectors.
Not needing a sled also comes in handy if you for instance need to prepare a drive for later to be permanently installed inside a computer or another enclosure of some kind. Very quick and easy.
It goes without saying that you should take care when inserting and removing a drive from the dock (as to not damage it's (or the dock's SATA and power connectors), but I've always taken care, even with my sled-based dock, so I don't see this as a problem.
And the OWC dock also takes 2.5" as well as 3.5" sized drives! This is great if you want to prepare (or clone) a laptop drive on another machine instead of having to first place it inside an external 2.5" drive enclosure. Excellent!
Which drive capacities are supported?
As mentioned earlier, one of my main reasons for looking into a new dock solution was because my old setup didn't take the newer, larger drives (i.e. above 2 or 3 TB). The specs don't say anything about this, and the user-manual only says "Supported drives: any 2.5" or 3.5" SATA drive". My rack-mounted drive bay was limited by the chips used in the Firewire-SATA interface (and couldn't be upgraded) so I contacted OWC about this and they responded "The USB-C Dual Bay solution should be able to handle up to 18TB+ drives." and in another mail said "... supports 3.5 and 2.5 SATA 6Gb/s drives and should be able to support up to 18TB HDD."
Slightly confusing if they mean up to 18 TB (as in "no more than 18 TB") or if drives beyond 18 TB can be used as well.
What I can say for sure is that I took my chances and ordered a Seagate Exos X16 (16 TB) drive for use as a backup drive and it works perfectly in the dock! I've also used it with a 3 TB Seagate Barracuda and a 3 TB Western Digital Caviar Green drive. They all work without a problem, and I assume all my other drives that I used with my old backup system will work fine as well.I haven't yet tried to insert 2.5" drives into it, but I see no reason why they wouldn't work. I've also tested a couple of 2.5" hard drives with it which worked without a problem, as expected. There's a separate (spring-loaded) "door" for those, so it's easy to insert the drive in the right place.
An estimated guess about that "up to 18 TB" or "18 TB+" stuff might be that 18 TB is (or was at the time I asked OWC about it -a year ago) the currently largest SATA drives you could get, hence that was what OWC could test the drive dock with. On the other hand it's a little strange that they don't have a definite answer as I'm sure the manufacturer has built the unit to OWC's ordered specs, so whoever designed it should know if it takes drives up to 18 TB or if you can go beyond that (and in that case, what will the largest capacity drives be whenever they'll become available).
In any case, 16 TB is more than enough for me, and I should be able to do away with a handful of smaller drives now!
Drive incompatibilities (or not)
OWC did mention that some drives sold by OWC have possible "wake from sleep" issues when attached to a Mac, so I'd stay away from these (they're rather low capacity by today's standards anyway):
- Toshiba TOSDT01ACA100 (1 TB)
- Toshiba TOSDT01ACA200 (2 TB)
- Toshiba TOSDT01ACA300 (3 TB)
I believe this is a general issue when using these drives with Mac computers and not something specifically to do with the drive dock. In other words: these drives are problematic in Mac environments regardless how they're attached to a Mac.
If I recall correctly there have been mentions of incompatible/problematic drives in (the quite lengthy) "Mac Pro 5.1 & high capacity drives" thread. Possibly elsewhere as well. I assume if a drive works with a Mac in a different enclosure or directly inside a Mac without a problem then the same drive would work just as well with this drive dock. If in doubt I'd check the drive model by searching or asking around in these forums before buying as some SATA drives are indeed "Mac-unfriendly" in different ways.
Individual drive power on/off switches
As usual you first need to eject a drive in MacOS/OSX (drag the drive's desktop icon over to the trashcan), so I do that, and once the desktop icon is gone (it's been ejected as far as MacOS/OSX is concerned) press the dock's drive power button (there's an on/off pushbutton for each drive) to power it off, then physically pull it out of the dock. I've never seen the need to turn off the power for the entire dock (there's a big switch on the back of it for that).
There's also an activity LED (dual coloured: blue and pinkish/red) for each drive dock to indicate that it's powered on (blue) and whenever data is accessed/written to the drive it flashes in a red/pink colour. This makes it very clear which drive bay is in use so you don't accidently risk removing it with it powered on.
NOTE: I was mildly frustrated at first about not getting to turn the power off with those pushbuttons. It turns out you have to press and hold the power buttons for 3 seconds. Had I taken the time to read the manual properly first would have known, so I blame this totally on myself (Powering on a drive bay on the other hand is just a matter of a normal, short button-press).
And thinking about it, this really is a great feature because it'll prevent you from accidently turning off a drive's power in the midst of a backup operation!
A power switch for each drive also means you can remove one drive while keeping the other drive running (very handy if you need to copy stuff from one drive over to several other drives).
Another great improvement over my old rack-based Firewire storage solution is that when you eject and physically remove one drive, the other drive doesn't get ejected as well! This used to happen all the time before, and I don't know if it's a Firewire issue, but I'm very happy to see that the two drive docks act completely independant of each other (at least if you properly eject and power down the applicable drive bay before removing a drive. I haven't done any extensive testing of this, but have always tried to do this correctly every time in order to avoid any possible problems with damaged files or whatever).
Internal power supply
Yes! The unit comes with a built-in power supply, so there aren't any external power adapters to be used. This means when you turn the unit off (by using the rear power switch) it actually shuts off power to the unit (unlike a "wall wart" power adapter which draws power (and generates heat/a potential fire harzard) even if the device it's connected to is switched off. According to the specs on the OWC product page it works anywhere between 100V to 240V 50/60Hz. I suppose the cable comes with a plug that suits the country it's sold in (I don't know as I've only bought one of these, and in my own country, and mine came with a standard plug which fits here).
Cables, connectors and other details
What else is there to say? The build appears excellent. It's compact (I have it placed on top of my Mac Pro and it even matches its silver colour!) and I love the fact that it has a built-in power supply. I usually have the rear power switch turned on, then press the applicable drive dock's power button to turn it on and off whenever I need to use a drive.
Cables included are:
- AC power cable (1m long)
- USB-C to USB-C (1m long)
- USB-C to USB-A (1m long)
Neither OWC's website nor the user manual mentions each cable's length, which is why I've stated them here. The USB socket at the back of the dock is a USB-C type (just in case you'd want to use another cable than those supplied). If I'm not mistaken you shouldn't exceed the 1m cable length limit if for maximum transfer speeds, but I haven't tested this so I really have no idea how much of a speed penalty you'd pay should you need to place the dock further away than 1m from the computer.
The unit is very quiet. Actually... silent! There's no fan inside, so all you hear are the hard drives inserted into its drive bays (unless they're SSDs that is, in which case you hear nothing)
Some people might see this is a downside (see thread comments below) as certain drives might overheat, but personally I think that having the bare drives "out in the open" without any enclosure covering it (apart from the very bottom/end section of a drive) gives it natural air cooling anyway. The drives I've been using seem to run at normal temperatures, so for me at least this hasn't been a problem.
Final conclusion
That just about concludes my (rather informal) review of this drive dock which I once again will say that I'm very happy with. I really can't find any fault or shortcoming with it.
My only slight frustrations prior to buying it was that I wasn't sure how large drives it would take (and any possible drive incompatibilities otherwise) and how long the supplied cables were. OWC really should add this information to their website as well as update its downloadable user manual (apparently there have been a couple of variations of this dock in the past: the (as far as I can tell) exact same dock with two Thunderbolt ports and a single USB 3.1 gen. 1 port, and another version with just a single USB 3.1 gen. 1 port).
The one reviewed here is the currently sold version with a single USB 3.1 gen. 2 port. The printed manual (really just a two-sided leaflet) included with the drive dock has indeed been updated and reflects the changes for this particular drive, but I wasn't able to find any downloadable manual on OWC's website for it. Either it hasn't been updated or I couldn't find it. Other than that, OWC has a clear winner on their hands in my opinion! 👍👍👍
I hope my review will be found useful for anyone considering buying this drive dock and that I've covered most of the important details
I'm using it with a mid-2010 Mac Pro running MacOS 10.13.6 High Sierra, and it's attached via a USB-C/USB-C cable to a Sonnet Allegro USB-3C-4PM-E (four 10 Gbps USB-C ports, dual controller chip) PCIe card. I haven't done any proper speed tests or anything, but from a user perspective it appears to back up just as fast as I did before with my Firewire-800 setup (more below) -I'm guessing faster as well had I done a speed test.
OK, last thing first (I know you're wondering): yes, I'm super happy with this drive dock!
Now on with the details....
Why I need this drive dock
To start off I have to add that I already had a fully working removable backup solution which I've used for many years already: a 4-bay 1U 19" rack-mounted Proavio Studiorack S4 connected via Firewire 800 to my mid-2010 Mac Pro. It allowed me to make external backups and backup archives (i.e. additional backups to keep in a physically different place than the usual backups in case of theft, fire, floods etc.) and has served me well for many years.
I've used Chronosync for this (and still am, now with the new drive dock) which I've found very good for doing backups other than Time Machine. It took me a little while to understand, but thanks to excellent support, great guides on their website and regular updates with improvements it's become a solid piece of software which I use all the time. Actually, once set up I don't have to think about it because everything happens automatically. I can now insert a backup drive in the dock and Chronosync starts up automatically and performs the backup. And it does this for all my different backup drives, so I really don't have to do much more than insert the drive(s) in the dock, power them on, then when everything's done I eject, power down the dock bay(s) and remove the drive(s).
There are other backup tools around, but I decided to give Chronosync a go when I first looked into doing backups (beyond Time Machine) and I haven't looked back since. I highly recommend it!
But back to the hardware... this setup worked well for years, but as my storage needs have grown I've outgrown that rack solution because it only takes 2 TB or 3 TB (I forget which) drives or smaller. This has resulted in many physical drives laying around which means more physical space needed and more hassle finding and inserting/removing drives whenver I need to backup.
And any new drives need to be mounted (with screws) in a new drive sled, so I had to buy a bunch of those as well. Firewire 800 was fine for me (as the Mac Pro has those ports) but newer computers don't, so it was time to look for something else....
The OWC dual drive dock ticks off just about all my boxes and more! Read on....
Two drive bays
Yes, it "only" has room for two SATA drives (not four as with my Proavio Studiorack) but actually I seldom need to access 4 drives at once. Without any sleds to mount it's so easy to just insert/remove a bare drive, so it's no problem exchange drives quickly, and you don't need to buy expensive and sometimes hard to find sleds for a particular type of dock. And since newer high capacity drives have a different screw mounting layout than all previous drives (i.e. the screw holes no longer match that of older drives) because of the larger platters inside you'd be getting problems if newer sleds aren't available or the ones you have cater for all SATA drives (for my Mac Pro I had to buy new drive sleds (also from OWC by the way) in order to remedy this. Not so when using high capacity hard drives with this dock -there simply isn't any permanent mounting of the drives to be done. Simply press the bare drive into its SATA connectors to attach it, and likewise to remove it you carefully pull the drive upwards. Each bay is covered by a spring-loaded "door" by the way, which is a nice touch to keep dust away from its SATA connectors.
Not needing a sled also comes in handy if you for instance need to prepare a drive for later to be permanently installed inside a computer or another enclosure of some kind. Very quick and easy.
It goes without saying that you should take care when inserting and removing a drive from the dock (as to not damage it's (or the dock's SATA and power connectors), but I've always taken care, even with my sled-based dock, so I don't see this as a problem.
And the OWC dock also takes 2.5" as well as 3.5" sized drives! This is great if you want to prepare (or clone) a laptop drive on another machine instead of having to first place it inside an external 2.5" drive enclosure. Excellent!
Which drive capacities are supported?
As mentioned earlier, one of my main reasons for looking into a new dock solution was because my old setup didn't take the newer, larger drives (i.e. above 2 or 3 TB). The specs don't say anything about this, and the user-manual only says "Supported drives: any 2.5" or 3.5" SATA drive". My rack-mounted drive bay was limited by the chips used in the Firewire-SATA interface (and couldn't be upgraded) so I contacted OWC about this and they responded "The USB-C Dual Bay solution should be able to handle up to 18TB+ drives." and in another mail said "... supports 3.5 and 2.5 SATA 6Gb/s drives and should be able to support up to 18TB HDD."
Slightly confusing if they mean up to 18 TB (as in "no more than 18 TB") or if drives beyond 18 TB can be used as well.
What I can say for sure is that I took my chances and ordered a Seagate Exos X16 (16 TB) drive for use as a backup drive and it works perfectly in the dock! I've also used it with a 3 TB Seagate Barracuda and a 3 TB Western Digital Caviar Green drive. They all work without a problem, and I assume all my other drives that I used with my old backup system will work fine as well.
An estimated guess about that "up to 18 TB" or "18 TB+" stuff might be that 18 TB is (or was at the time I asked OWC about it -a year ago) the currently largest SATA drives you could get, hence that was what OWC could test the drive dock with. On the other hand it's a little strange that they don't have a definite answer as I'm sure the manufacturer has built the unit to OWC's ordered specs, so whoever designed it should know if it takes drives up to 18 TB or if you can go beyond that (and in that case, what will the largest capacity drives be whenever they'll become available).
In any case, 16 TB is more than enough for me, and I should be able to do away with a handful of smaller drives now!
Drive incompatibilities (or not)
OWC did mention that some drives sold by OWC have possible "wake from sleep" issues when attached to a Mac, so I'd stay away from these (they're rather low capacity by today's standards anyway):
- Toshiba TOSDT01ACA100 (1 TB)
- Toshiba TOSDT01ACA200 (2 TB)
- Toshiba TOSDT01ACA300 (3 TB)
I believe this is a general issue when using these drives with Mac computers and not something specifically to do with the drive dock. In other words: these drives are problematic in Mac environments regardless how they're attached to a Mac.
If I recall correctly there have been mentions of incompatible/problematic drives in (the quite lengthy) "Mac Pro 5.1 & high capacity drives" thread. Possibly elsewhere as well. I assume if a drive works with a Mac in a different enclosure or directly inside a Mac without a problem then the same drive would work just as well with this drive dock. If in doubt I'd check the drive model by searching or asking around in these forums before buying as some SATA drives are indeed "Mac-unfriendly" in different ways.
Individual drive power on/off switches
As usual you first need to eject a drive in MacOS/OSX (drag the drive's desktop icon over to the trashcan), so I do that, and once the desktop icon is gone (it's been ejected as far as MacOS/OSX is concerned) press the dock's drive power button (there's an on/off pushbutton for each drive) to power it off, then physically pull it out of the dock. I've never seen the need to turn off the power for the entire dock (there's a big switch on the back of it for that).
There's also an activity LED (dual coloured: blue and pinkish/red) for each drive dock to indicate that it's powered on (blue) and whenever data is accessed/written to the drive it flashes in a red/pink colour. This makes it very clear which drive bay is in use so you don't accidently risk removing it with it powered on.
NOTE: I was mildly frustrated at first about not getting to turn the power off with those pushbuttons. It turns out you have to press and hold the power buttons for 3 seconds. Had I taken the time to read the manual properly first would have known, so I blame this totally on myself (Powering on a drive bay on the other hand is just a matter of a normal, short button-press).
And thinking about it, this really is a great feature because it'll prevent you from accidently turning off a drive's power in the midst of a backup operation!
A power switch for each drive also means you can remove one drive while keeping the other drive running (very handy if you need to copy stuff from one drive over to several other drives).
Another great improvement over my old rack-based Firewire storage solution is that when you eject and physically remove one drive, the other drive doesn't get ejected as well! This used to happen all the time before, and I don't know if it's a Firewire issue, but I'm very happy to see that the two drive docks act completely independant of each other (at least if you properly eject and power down the applicable drive bay before removing a drive. I haven't done any extensive testing of this, but have always tried to do this correctly every time in order to avoid any possible problems with damaged files or whatever).
Internal power supply
Yes! The unit comes with a built-in power supply, so there aren't any external power adapters to be used. This means when you turn the unit off (by using the rear power switch) it actually shuts off power to the unit (unlike a "wall wart" power adapter which draws power (and generates heat/a potential fire harzard) even if the device it's connected to is switched off. According to the specs on the OWC product page it works anywhere between 100V to 240V 50/60Hz. I suppose the cable comes with a plug that suits the country it's sold in (I don't know as I've only bought one of these, and in my own country, and mine came with a standard plug which fits here).
Cables, connectors and other details
What else is there to say? The build appears excellent. It's compact (I have it placed on top of my Mac Pro and it even matches its silver colour!) and I love the fact that it has a built-in power supply. I usually have the rear power switch turned on, then press the applicable drive dock's power button to turn it on and off whenever I need to use a drive.
Cables included are:
- AC power cable (1m long)
- USB-C to USB-C (1m long)
- USB-C to USB-A (1m long)
Neither OWC's website nor the user manual mentions each cable's length, which is why I've stated them here. The USB socket at the back of the dock is a USB-C type (just in case you'd want to use another cable than those supplied). If I'm not mistaken you shouldn't exceed the 1m cable length limit if for maximum transfer speeds, but I haven't tested this so I really have no idea how much of a speed penalty you'd pay should you need to place the dock further away than 1m from the computer.
The unit is very quiet. Actually... silent! There's no fan inside, so all you hear are the hard drives inserted into its drive bays (unless they're SSDs that is, in which case you hear nothing)
Some people might see this is a downside (see thread comments below) as certain drives might overheat, but personally I think that having the bare drives "out in the open" without any enclosure covering it (apart from the very bottom/end section of a drive) gives it natural air cooling anyway. The drives I've been using seem to run at normal temperatures, so for me at least this hasn't been a problem.
Final conclusion
That just about concludes my (rather informal) review of this drive dock which I once again will say that I'm very happy with. I really can't find any fault or shortcoming with it.
My only slight frustrations prior to buying it was that I wasn't sure how large drives it would take (and any possible drive incompatibilities otherwise) and how long the supplied cables were. OWC really should add this information to their website as well as update its downloadable user manual (apparently there have been a couple of variations of this dock in the past: the (as far as I can tell) exact same dock with two Thunderbolt ports and a single USB 3.1 gen. 1 port, and another version with just a single USB 3.1 gen. 1 port).
The one reviewed here is the currently sold version with a single USB 3.1 gen. 2 port. The printed manual (really just a two-sided leaflet) included with the drive dock has indeed been updated and reflects the changes for this particular drive, but I wasn't able to find any downloadable manual on OWC's website for it. Either it hasn't been updated or I couldn't find it. Other than that, OWC has a clear winner on their hands in my opinion! 👍👍👍
I hope my review will be found useful for anyone considering buying this drive dock and that I've covered most of the important details
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