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75 votes

External drive does not mount after plug off without eject

SOLVED. Had this problem today. OLD external drive, had its own power source, plugged into a surge protector. I hit the power button on the surge protector when I was unplugging something else, and ...
stereof's user avatar
  • 751
69 votes

External drive does not mount after plug off without eject

I'd recommend checking if fsck is holding your disk hostage upon connection. This was it for me. Running ps aux | grep fsck revealed: root 2587 7.3 0.1 4363584 21780 ?? U 10:...
Ariel Allon's user avatar
  • 1,886
31 votes
Accepted

How to know whether Mac has SSD or HDD installed

Apple Menu -> About This Mac -> System Report Select Storage in the Hardware section Select "Macintosh HD" on top Alternatively you can run system_profiler SPSerialATADataType or system_profiler ...
nohillside's user avatar
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12 votes
Accepted

HFS+ vs APFS: What are the pros/cons of converting HDDs to APFS?

APFS (Apple File System) compared to HFS+ Almost all differences apply to Solid State Drives (SSD) and Hard Disk Drives (HDD) as well, while users of HDDs may not see an improvement in speed. APFS ...
oa-'s user avatar
  • 7,716
12 votes

How do I make an HDD as fast as an SSD?

I'm afraid that's impossible. Your hard drive is essentially not much different from an old record turntable: it has spinning disks and a 'head' that writes or reads the magnetic stripe at a point on ...
benwiggy's user avatar
  • 35.3k
10 votes

How to recover data from formatted encrypted external hdd?

Unfortunately, it’s gone. When you encrypt your drive, it gets scrambled with a randomized key so, if you were to look at the actual sectors of the drive, it would just be a jumbled mess. The key is ...
Allan's user avatar
  • 100k
10 votes

How do I make an HDD as fast as an SSD?

SSD are designed like a car. HDD are trucks. You can’t make a truck operate like a car unless you buy a car and call it a truck. Diesel fuels most trucks and some cars (computer “fuel” is SATA ...
bmike's user avatar
  • 235k
9 votes

How to know if Drive is SSD or HDD through Terminal?

A super fast way to do this is to use diskutil to get this info: diskutil info disk0 | grep "Solid State" You will receive a "Yes/No" answer similar to the following: Solid State: Yes ...
Allan's user avatar
  • 100k
8 votes

External drive does not mount after plug off without eject

If you can see it in diskutil list, locate its identifier (comes in the form of /dev/diskx) and run: diskutil mountDisk /dev/diskx while replacing /dev/diskx with your disk identifier. If even that ...
perhapsmaybeharry's user avatar
7 votes
Accepted

Do I have an HDD or an SSD in my MacBook?

All retina Macbook Pros have PCIe SSDs. Previous MBPs (2012 + earlier) shipped with HDDs. To find this out, find your model information by going to Apple (top left corner of the screen) -> About this ...
NoahL's user avatar
  • 3,507
6 votes

Replacing HDD with SSD; what about non-APFS/APFS?

No, you don't need to convert the HDD. I recently did exactly what you're doing (though I installed the new SSD myself, which meant not having to worry about erasing the HDD) and didn't have to do any ...
dhnyny's user avatar
  • 179
6 votes

macOS Catalina - can't mount external hdd - verification/reading of the omap object failed: Illegal byte sequence

I had the same problem (invalid o_type (0x40000003, expected 0x4000000b)) after an upgrade of an OS to 10.15.3 and I was able to fix it in a very bizarre and unexpected manner. I added another APFS ...
Alexei Masterov's user avatar
5 votes
Accepted

How to install or port data to a Fusion / Hybrid / SSHD drive

No, there is nothing special you need to do. At the risk of oversimplifying things, the way that hybrid drives work is that they monitor the data being read from the drive and, over time, they ...
Monomeeth's user avatar
  • 64.4k
5 votes

Do I have an HDD or an SSD in my MacBook?

In Sierra Go to "About this Mac" on the top left of the screen in the Apple menu. Click on the Storage tab. This shows all attached drives. For SSD it shows as "Flash Storage"
mmmmmm's user avatar
  • 30.1k
5 votes

Which format should I choose for a Time Machine backup volume?

Time Machine in Catalina only supports HFS+ as a destination volume. The first macOS that supports APFS as a destination volume is Big Sur. ref: https://support.apple.com/guide/mac-help/types-of-...
Marc Wilson's user avatar
  • 5,746
5 votes
Accepted

How can I speed up a slow iMac from 2017?

Here I assume your iMac (21.5 inch, Mid 2017) was original equipped with only a HDD and no SSD. In other words, there was no prior Fusion drive arrangement. In this case, you can only internally ...
David Anderson's user avatar
4 votes
Accepted

Installing macOS on a new HDD from USB drive stuck on grey screen with Stop sign

My old MacBook Pro is a mid 2009 model which is not supported by macOS Sierra. - Only MBPs Mid 2010 and later are supported. I created an bootable USB disk from El Capitan (which I re-downloaded ...
brahmana's user avatar
  • 161
4 votes
Accepted

How to upgrade SSD from HDD for my mac book pro

You should look at the ifixit HDD replacement guide for this model. This will show you exactly the steps you need to take, including 'unplugging' the logic board from the battery. You may want to buy ...
benwiggy's user avatar
  • 35.3k
4 votes

How do I make an HDD as fast as an SSD?

If you want to make a hard drive run as fast as an SSD, install lots of RAM, and put the system to sleep rather than shutting it down when you're finished. If you've got enough RAM (in my experience, ...
Mark's user avatar
  • 561
4 votes
Accepted

APFS vs Mac OS Extended (Journaled) for external HDD

APFS is known to not perform well on spinning disk drives (non SSDs). Developer of Carbon Copy Cloner: An analysis of APFS enumeration performance on rotational hard drives | Carbon Copy Cloner | ...
TJ Luoma's user avatar
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4 votes
Accepted

Where is the DMG saved when the hard disk is erased?

First of all, the process has evolved as newer versions of OS X and macOS have been released. Basically, you have the right idea. When booting to macOS Recovery, one or more ramdisks are created. The ...
David Anderson's user avatar
3 votes

How to install or port data to a Fusion / Hybrid / SSHD drive

Strictly speaking, this won't be a Fusion drive as far as OS X 10.8 or 10.10 are concerned. The operating system will see the new part as a single drive, and Seagate's firmware will do all the "Fusion"...
samh's user avatar
  • 4,121
3 votes

External drive does not mount after plug off without eject

That has happened to me many times. Go to Launch Pad, Disk Utility, and select the disk that won't mount. Then select Repair.
TDM's user avatar
  • 394
3 votes

Macbook Pro 2011 SSD Placement Location

There will be no problem. A SATA SSD has the same connectors as a SATA HDD drive so the connectors are identical. To use you SSD in the optical bay, a optical bay drive kit is required. You simply ...
Allan's user avatar
  • 100k
3 votes
Accepted

Copy single file with I/O errors

Aside from dd there is also ddrescue although it's not a native OS X/macOS utility, however it can be installed in a number of ways. Personally I prefer to compile directly from source code however ...
user3439894's user avatar
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3 votes
Accepted

Safe to unplug external HDD that has spun down?

Your best bet is to always eject (or unmount) the drive. Basically, failure to unmount before disconnecting the device can result in loss of data and/or a corrupted file system. If the external ...
Monomeeth's user avatar
  • 64.4k
3 votes
Accepted

Is it possible to mix APFS and HFS+ volumes on the same physical disk?

Well, you would need a separate partition for each volume type. In other words, APFS type partitions can hold multiple volumes, but each must be a APFS volume. HFS+ type partitions can hold a single ...
David Anderson's user avatar
3 votes
Accepted

How to reuse HDD from TimeCapsule without losing the data?

This happens because the TimeCapsule disk contains 3 partitions with the same UUID (so much for being Universally Unique) equal to all "0". macOS comes with a utility to assign a new random ...
Andrew Morozko's user avatar
3 votes

How to keep external HDDs spinning (prevent spinning down) on macOS?

You can workaround this by following solution: Turn on OSX native terminal.app application and paste following command (and leave terminal.app running): ping -i 300 127.0.0.1 > /Volumes/WD1/wake_up....
Sid's user avatar
  • 139
3 votes

Ensure data of an iMac is gone and unrecoverable

Disk Utility has a secure erase function. Open Disk Utility Select the disk that you wish to erase Select the Erase tab Click on the Security Options... button Move the slider to Most Secure Click ...
Greenonline's user avatar
  • 1,865

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