Using external USB-disks for mainstorage

[Ravn]

Dear FreeNAS community,

I am thinking about using external USB disks for primary storage. Is this a bad idé for any reason. This system will serve me at home with a low load.

Kr,
Robert

 

[Samuel Tai]

Is this a bad idé for any reason.

Yes, this is a VERY BAD IDEA. Just search through the forums. Many people have lost their pools constituted on external USB drives because:

• They forgot to put the drives on a UPS along with the main system, and blew out their pools on a power bump
• USB chipsets on the USB->SATA adapters aren't designed to handle heavy IO, and it's easy to overstress them, like during a scrub
• USB motherboard chipsets have a disturbing tendency to lock up at inopportune times

 

[garm]

What about UASP?
There is no FreeBSD driver, but Scale might be able to use it?

 

[Samuel Tai]

I have an external UASP dock that I only use for zeroing out drives. Even in this limited use case, I'll see the drive occasionally drop out after a certain amount of time.

 

[Adrian]

I use external USB 3.1 single disk enclosures with single disk pools for backup and transfer, with no major problems (so far).
A minor problem is that sometimes a disk is not seen until replugged in the other port.
This is with quite expensive enclosures and USB cards.

However I would be very chary of using such for primary storage. Your data will be much safer on internal disks.

Have you looked at the Resources section, especially https://www.ixsystems.com/community/resources/hardware-recommendations-guide.12/ ?

 

[sretalla]

All components in a system will eventually die or fail or become unreliable at some point... you just need to ask yourself: Do I want a system where that's going to happen much sooner than I want or expect?

I personally used some USB disks as a temporary measure at one point several years ago and was initially comfortable enough to leave it for a bit longer (2-3 months), which I regretted soon after. I attempted to replace enclosures and cables, changed USB ports... all followed closely by failure.

Either the external enclosure and its controller will fail or port resets will drop disks from your pool, or both. Depending on the manufacturer (I'm looking at you, Marvel) you may even see the USB controller pack it in entirely.

Your SMART data will almost certainly not be complete or accurate either (if you can get any at all), so there's also a chance of unanticipated disk failure.

In summary, don't do it to yourself... or at least don't use ZFS if you're going to do it (that also means don't use FreeNAS), USB controllers can't handle the IO patterns that ZFS generates. There are plenty of Linux alternatives for you to work with.

 

[garm]

Bother... I was kind of hoping to build my BrickNAS on a Pi4 and startech uasp enclosure...

 

[garm]

Your SMART data will almost certainly not be complete or accurate either

Well that’s the point is UASP, it’s SCSI over usb

 

[Yorick]

Bother... I was kind of hoping to build my BrickNAS on a Pi4

Absolutely not for FreeNAS/TrueNAS, that thing isn't kidding when it says "8 GiB minimum RAM". There are other options that are not ZFS-based that are a much better fit for Pi4.

 

[garm]

Absolutely not for FreeNAS/TrueNAS, that thing isn't kidding when it says "8 GiB minimum RAM". There are other options that are not ZFS-based that are a much better fit for Pi4.

No no, BrickNAS is a small “cheap” single disk, network agnostic backup target based on Debian or something. Been looking for the hardware for quite some time now...