External drives that keep disconnecting from your Mac
If your external drive keeps ejecting itself, the little chip inside the enclosure may be to blame.
Many external hard drives and enclosures use a small bridge chip to connect the drive to USB. Different manufacturers use different chips, and some get along with Macs better than others.
What we've noticed
Enclosures with ASMedia chips generally behave well on Macs. Some with JMicron chips have a reputation for random disconnections, although plenty work fine. Makers sometimes change the chip between batches, so the same model can vary.
Check yours
- Plug the drive in.
- Open System Information (hold Option and choose it from the Apple menu).
- Click USB and select the drive.
- Look at the Vendor ID: 0x174c is ASMedia, and 0x152d is JMicron.
Other common culprits are tired cables, unpowered hubs, and drives going to sleep. For a backup drive, it's worth getting this right.
Want a hand with this?