Should I eject my external SSD before sleeping my Mac?

HWTech wrote:

I don't know how macOS handles an ejected device after waking from sleep, but I do know that if you "eject" a drive within macOS (default option when using the Finder--it combines unmounting & ejecting), then the drive must be physically disconnected & reconnected before it will be seen by macOS again.

After ejecting a drive in the Finder, I left the drive physically connected and went into Disk Utility. The drive and unmounted volume were visible in Disk Utility. Mounting the volume in Disk Utility made it appear in the Finder.

There seems to be a bit of history with Macs sometimes improperly dismounting external USB drives during Sleep. While I wish that wasn't the case, you might encounter the issue.

If you do decide to eject your external SSD before putting your Mac to Sleep, I don't think there is any need for you to also unplug it. When you wake the Mac, the Mac may remember that you wanted to eject the drive, and you may need to re-mount the drive using Disk Utility. That could be a bit inconvenient.

These days, I use Lock Screen or Shut Down, and shut off my monitor. When I turn the monitor back on, a key press or mouse click gets the Mac Studio to realize that it should try talking to the monitor again.

The issue appears to be FAR more common with Bus-powered drives without an independent source of power.

When the Mac sleeps, recent Macs drop USB-power to "standby" levels. This is a fairly recent innovation, so many drive enclosures, engineered a while ago, are not prepared to degrade gracefully. Instead, they simply drop out, causing annoying disconnect issues that may require a Disk Utility Repair/FirstAid to set right again.

Servant of Cats wrote:

After ejecting a drive in the Finder, I left the drive physically connected and went into Disk Utility. The drive and unmounted volume were visible in Disk Utility. Mounting the volume in Disk Utility made it appear in the Finder.

Yes...that has also been my experience with external drives.

Servant of Cats wrote:

If you do decide to eject your external SSD before putting your Mac to Sleep, I don't think there is any need for you to also unplug it. When you wake the Mac, the Mac may remember that you wanted to eject the drive, and you may need to re-mount the drive using Disk Utility. That could be a bit inconvenient.

I don't know how macOS handles an ejected device after waking from sleep, but I do know that if you "eject" a drive within macOS (default option when using the Finder--it combines unmounting & ejecting), then the drive must be physically disconnected & reconnected before it will be seen by macOS again.

Unmounting all volumes on a drive will allow macOS to give the user an option to re-mount any of those volumes without needing to disconnect & reconnect the drive. The only way I am aware to just "unmount" a volume without also "ejecting" the drive is by using Disk Utility or by using the command line.

Servant of Cats wrote:

HWTech wrote:

I don't know how macOS handles an ejected device after waking from sleep, but I do know that if you "eject" a drive within macOS (default option when using the Finder--it combines unmounting & ejecting), then the drive must be physically disconnected & reconnected before it will be seen by macOS again.

After ejecting a drive in the Finder, I left the drive physically connected and went into Disk Utility. The drive and unmounted volume were visible in Disk Utility. Mounting the volume in Disk Utility made it appear in the Finder.

It seems it can vary. I just tested a USB stick with two partitions on it.

If I eject the one partition, but decline to eject all partitions/volumes, then I can use Disk Utility to re-mount the "ejected" partition/volume.

If I eject the last mounted partition individually (decline to eject them all), then after "ejecting" the last mounted partition/volume, the drive disappears completely from the system and requires physically disconnecting the drive from the computer & physically reconnecting the drive. The same thing occurs when I eject one partition, then select "Eject All" option that pops up.

I don't have a drive at the moment which contains just one mountable volume to test, but I am sure the same thing occurs there as well since I cannot recall ever being able to re-mount an ejected drive.

Currently testing using a MBPro M2 laptop running macOS 13.6.9 Ventura. Both volumes were FAT32.

I recall the same thing with HFS+ volumes previously.

HWTech wrote:

It seems it can vary.

It certainly appears that way. In my case I have never encountered these problems.

If I sleep my Mac, all the drives are still there when it wakes.

If I eject a drive (or partition or volume) but keep it physically connected, I can always use Disk Utility to remount the drive (or partition or volume). I have never had to uplug & replug a drive to remount it.

Most of my external drives are powered but one is bus powered. No difference in my experience. It has worked this way as long as I have been using Macs ... from Panther to Monterey, G4, G5, i5, i7, i9, FireWire, USB, HFS+, APFS, FAT32, ExFat.

Maybe things have changed with the advent of Apple Silicon ... but I don't have an M-series machine to test.

Yeah, don't worry about it, but there is a setting... Energy Saver>Put Hard Disks to sleep if possible.

BDAqua wrote:

Yeah, don't worry about it, but there is a setting... Energy Saver>Put Hard Disks to sleep if possible.

I don’t think that applies to SSDs who have no need to “sleep”.