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Comment by georgyo | Hacker News Reader

I don't know if I am at all surprised that a USB hard-drive is failing to implement all SCSI commands, even if it really should.

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You're getting replies about shucking, but WD Passports are 2.5 inch drives that AFAICT are USB-only. The drive controller speaks USB directly, as opposed to SATA chained to a translator chip on a separate board. I've got a pair on my desk which I won't attempt to open, as I'm actually using them as portable external drives (as opposed to my pile of easystore carcasses).

I haven't noticed any abnormal behavior, but I also don't mount/luksOpen them with -o discard (if that's what it takes to trigger this).

You can see it visually too if you have a 2.5-inch drive to compare it to (or know the size of a 2.5-inch drive): drives with separate USB to SATA boards are longer to fit that board, while these are only about the same length as the bare drive plus the plastic shell.

https://www.youtube.com/watch?v=2GGTQF6oE3E

Weird. That's interesting. Why did I think WD and other companies would just keep churning SATA interface drives forever and ever.

Wonder if the physical hdd part itself is identical to the SATA models, and swapping over the control board from a (eg dead) SATA one of same capacity (& platters) would work?

Unlikely, in a modern (high capacity) drive, the firmware contains quite a bit of calibration data for all the components. You'd probably have to perform a factory reset and reformat of the physical disk blocks.

Good point. Probably not useful for extracting existing data from a (eg dead) drive. :)

Isn't the USB mass storage spec just a pipe for sending SCSI commands?

USB Mass Storage has its own command set. Some newer USB3 adapters do allow SCSI commands to be passed through using UASP, but not all do.

Some, if not most, USB2 to SATA/SAS bridges also allows passing these commands. smartctl can talk with most of the bridges to pass-thru commands, at least for SMART purposes.

Seagate's 3.5" Backup Plus Hub drives mask the disk itself intentionally to show itself as a different, generic Seagate device, probably to prevent people from messing with the disk settings and identifying the disk itself.

And even if they support it, it isn't always safe to do so. For example, I have a WD Passport sitting on my desk that was bricked when I issued an ATA secure erase command[1]. Don't assume that any SATA/SCSI commands are safe to issue to USB drives unless you have researched it.

[1] https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase

Probably the USB interface keeps some data for its encryption function on a part of the hard drive which it makes inaccessible. You erased the whole hard drive, including that part, and probably caused the USB interface to malfunction.

No, it famously lacks TRIM for example. They may finally have gotten their act together and updated it in a recent version, but there are plenty drives on the market still today that will , for lack of TRIM support, eventually grind themselves down to a halt. FireWire and Thunderbolt do support full SCSI, iirc.

I also recently tried a bunch of USB3+SCSI - SATA adapters from Amazon, and only found a single one that supported passing TRIM through. And that's after a firmware upgrade that can only (afaik) be done using an installer running on ARM+Linux and provided by a third-party. Truly amazing.

How can I check that for my adapter?

Either mount the drive and run "fstrim" on the drive's location (it will error without TRIM support) or https://unix.stackexchange.com/a/339684/21419

You need to check your adapters for UASP support.

In addition to devices, the host controller has to support UASP too - in early days of USB3, it was separately licensed option.

All the adapters I tried claimed UASP support.

If the drive itself doesn't support it how can the interal usb controller in an external drive compensate? At best it seems it could hide the error or do some hacky compensation for it.

At best perhaps it's a method of enforcing product segmantation - preventing users from buying & shucking what are strangely cheaper external drives (discounted so that WD can sell you (or sell 'you' via telemetry) some value addon software. I don't see a technical reason for how a drive could physical be unable to support this SCSI command.

Why wouldn't it have the same functionality as an internal HDD?

They were never ever intended to be taken out and used that way. You can mask potential firmware problems and ship faster if you also own the enclosure.

Wouldn't it ship faster if you just plopped in any regular ol HDD the company makes (the cheapest one, probably) instead of developing a custom one just for that product?

In reality, it is probably exactly that. These are the drives that didn't make the cut to be sold independently.

Yeah pretty common thing across all industries. I would expect things like maybe the vibration is slightly out of normal spec, or an abnormal amount of bad sectors on a fresh unit.

But I don't understand how them maybe not being top quality would make part of the SCSI protocol disappear in the firmware. That indicates that these drives had a different firmware developed for them with missing features which makes no sense.

What you are missing is that WD Passports are 2.5 inch drives that are USB-only. The drive controller speaks USB directly, as opposed to SATA chained to a translator chip on a separate board.

They implement certain parts not pass through and do indeed have separate USB firmware.

If you're trying to bring a new drive to market (and even for many capacities, they get refreshed regularly if only to cut platters or find new ways to cut costs), and your firmware isn't ready for prime time as an internal drive, you can still ship it as an external drive earlier because you have a good idea of how the controller is going to treat the drive. Not only do the external drives tend to be the end of the waterfall in terms of quality, manufacturers also may ship with firmware problems that would be a stop ship if it was packaged for nearline or desktop.

Don't ask me how I know this.

I was always wondering how external drives can be cheaper than internal. This explains. Thank you.

Yeah, and massively cheaper too. I bought a 5TB passport drive for £71 recently, an equivalent capacity desktop drive would be at least £200. The price disparity is insane.

And then consumers use external drives as a backup method...

Yes, if there's a take away for me, having seen how the sausage is made, it's far and above worth grabbing as NAS or nearline SATA drive and jamming it in a good SATA enclosure instead of buying a drive that's already in an enclosure if you want peace of mind.

Didn’t backblaze do exactly this (shuck drives from external enclosures) when they couldn’t buy enough drives on the open market after the tsunami?

They did but with 3.5" drives which were not USB specific. This is done to save space and noone cares for space with a 3.5" drive. If you ship with a converter board it is impossible to make it this small.

And they themselves said that it's not a good idea, it simply was a time of desperation. They're not shucking externals now, now that proper drives are available.

Also they have a lot more tolerance for disk failure than almost anyone.

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