WD MyBook Duo (JBOD) - Unraid only sees 1 disk instead of 2

[jrmcmillan]

I am a NOOB setting up Unraid as a backup server.  I have a couple of WD MyBook Duo's ("MBD"), which are USB DAS enclosures, that I'm trying to use for the array.  One MBD has 1 - 4TB drive and the other MBD has 2 - 4TB drives.  Both are configured as JBOD.  The idea is to use the one MBD with 1 - 4TB drive as the parity drive and the other MBD with 2 - 4 TB drives for data storage.  This issue is Unraid only sees one of the drives in the MBD with 2 disks instead of both of them.  FYI - Windows 11 sees both drives separately in the MBD with 2 drives - as it should.

 

I've searched other threads but didn't really find any solutions.  I know I can use these MBD's as unassigned devices, but that doesn't give me any data protection.  My longer-term solution is to use a USB drive enclosure that will house those 3 drives, and perhaps more over time.  But, Unraid needs to be able to see each disk individually for this to work.

 

Thanks in advance for any help.

[Hoopster]

17 minutes ago, jrmcmillan said:

My longer-term solution is to use a USB drive enclosure that will house those 3 drives

USB enclosures and USB-connected drives are not recommended for use in an Unraid array.  USB connections for "permanent" storage can be very unreliable and will often randomly disconnect.  This is not good for parity-protected array.  The issue often comes down to motherboard and chipset implementations of USB; they vary widely.  For this reason, USB connections for parity and array drives are not recommended.  For unassigned devices, it is less critical.

 

Unraid tracks disks by serial number.  Some enclosures are known to not present unique serial numbers for each disk in the enclosure.  If this is the case, Unraid will not see the individual disks.  I have no idea if that is the issue with your My Book Duo, but it is a possibility.

Edited May 26 by Hoopster

[jrmcmillan]

I appreciate the info.  I'm guessing your thought that the MBD is only presenting one serial number is likely the issue.

 

I've been using USB DAS's on Windows PC's as both my primary and backup drives (both with hardware raid) for years and never had an issue with a disconnect - or anything else for that matter.  The idea of using Unraid to create a "real" server is attractive to me as a learning experience while trying to reuse existing hardware.  My "server" is actually a mini-PC with essentially no additional storage options other than USB drives.  I've had it running for a couple of weeks with these drives as unassigned devices without parity protection - which worked fine - and thought I'd try setting them up as an array with parity.

 

I will have access to a different USB enclosure in a few days.  I'll try that to see if I can see all the drives in Unraid.  Thanks again.

[Hoopster]

2 minutes ago, jrmcmillan said:

never had an issue with a disconnect - or anything else for that matter.

Some people have no problems with USB connected disks on Unraid.  They are just not recommended because they can be problematic and there is no way to predict if it will work or not without trying it on your hardware.   It is highly dependent on how well the motherboard manufacturer implemented USB and it may vary between versions of USB.

[Hoopster]

There are times, such as parity checks and disk rebuilds, when all drives are being accessed simultaneously.  In these situations is when USB is most likely to drop a connection.  It could happen randomly on a single active disk, but its more likely to happen when the interface is under heavy load from multiple disks trying to communicate at the same time.

[jrmcmillan]

Appreciate the additional info.  Since this server is really just a backup of a backup, I'll try it out and see what happens.  Under the circumstances, I think I can live with the risk.