Seagate External HDD won't show up.

I am having the same issue, and appreciate your questions here. Ive recently updated to El Capitan.

I have another seagate drive and it is working fine.

Ive tried swapping cables etc an using new power sources. The disk starts up but just wont reflect on the Mac at all.

This puzzling problem just started on one of our external drives last month. It's a low priority drive so I haven't looked closely at the problem until today. Seagate 3T disappeared from the mac server's finder but is still visible to everyone on the network. That's fine since they use it to store files that are ready for deletion anyway but I'm troubled why I can't see the drive on the server. I literally have to log on to the LAN remotely on my MBP to view it and move files around. Which is slow as cricket compared to working off the server.

• Disk Utility see's it and it's healthy

• Finder prefs show's external drives checked

• sidebar drive panel set to "show"

• I can mount and dismount the drive on disk utility

• I've rotated all USBs and same issue

• I've moved the 3T drive to other computers and it won't show up on the their finder either

My network configuration:

We work on a six Mac LAN connected to a Mac Mini server that serves up a 6T, 3T and another 3T

6T working is on Thunderbolt

3T is on Thunderbolt

3T is USB 3.0

I am having this trouble too. Any advice or help please???

You are better off starting your own discussion. Include:

- Does it show in Profiler

OS X: About System Information and System Profiler - Apple Support

- Does it show in Disk Utility? If so what is listed about the drive?

- Can yo hear/feel the disk spinning?

- Do the lights on the enclosure light?

- Did it "work" before?

- Does it show on another computer?

If you can't find the solution above in this thread then start your own thread because you in fact do not have the same problem then.

For me the solution was to select the external hard drive in Disk Utility then I clicked on the "Mount" icon at the top.

STILL NEED HELP:
I just ran a first-time backup with my new Seagate 1T drive, and that first time plugged in I ran a 6-hr Time Machine backup. Since running that, each time I plug in, the device is not found. The external drive light comes on, remains on, and I can hear it whir for a couple seconds but it shows up nowhere on my MacBookPro. The only place it appears to be acknowledged is under the USB hardware screen (farthest right window). I have tried plugging it in & out of either USB port (one on each side of laptop), tried restarting with or without external drive plugged in, etc. The packaging on the Seagate drive indicates it is compatible with 2.0 or 3.0 USB. El Capitan 10.11.1 is my most recent software - asking for upgrade to be installed but requires more than 4GB space for that upgrade, which I do not have on laptop hard-drive, hence the need for external drive.

- Try resetting the SMC

Resetting the System Management Controller (SMC) on your Mac

- Try another cable

- Try on another computer

If still problem seems like a problem with the enclosure or the disk. System Profiler should fully identify the disk including the capacity, which is not your case

I tried the SMC, including battery removal, and am experiencing no changes. The 1TB drive is brand new. I do not have another cord, nor another computer to try the external drive with, unfortunately. Any suggestions? This is the updated screen shot since performing the SMC. I am using WiFi.

Try on another computer to confirm that either bad enclosure or disk or bad cable

I am also looking for help. My Seagate Backup Plus portable 2 TB drive won't show up on either computer, not in disk utility, not under Devices in the sidebar. The light goes on and I can feel the drive spinning. I restarted my computer. Both computers are running El Capitan. The drive has been working until I tried to erase it. The erase failed and when I tried to find out why I lost that window and the drive disappeared. I am grateful for any advice.

Thank you for help!

- Does it show in System Profiler under USB? You should see the chipset in the enclosure as well as the HD itself

OS X: About System Information and System Profiler - Apple Support

you should see both the enclosure and the HD itself.

Have you tried another cable?

Could be that the drive inside failed or the enclosure failed.

I have tried another cable. It does not show up in the system profiler. The light goes on and it feels like the drive is spinning when I hold the case.

Your symptoms could be an indication that the drive died when you tried to erase it.

A drive that cannot tell Disk Utility its Make&Model, and a sensible, non-zero size/capacity, has died.

The most frequent cause of death of external drives is the converter-card in the enclosure. If a standard drive was used, the drive can be sometimes be removed and placed in a new enclosure, and may be fine.

But some manufacturers combine the adapter card onto the drive card, and death of that card cannot be fixed.

Thank you for this excellent information. I imagine that along with low prices we have to expect less than excellent reliability. It teaches me that 2 back ups is not redundant.

Happy New Year to you and all the people who generously share their knowledge.