Understand how physical storage attached to a computer inside and out, is seen by users, but equally importantly how it is seen by the system. Learn what the system sees when it sees storage, from the Unix command line level. Learn concepts such as a format, a partition scheme, a pool, an affinity, and more. Learn how SSD speed improvements affect computer speed, reads are getting faster and faster, while writes are getting slower. Learn how 3000 write cycles are about all you get before the data block is TRIM'd out of the storage use pool. Learn what the Spinning Pinwheel of Death really means, and how to look at it as a troubleshooter. All it means is that an application hasn't been keeping on top of it's I/O.
- [Instructor] In Mac OS, storage and file systems are undergoing a bit of an upheval in the last few years, and we're adding to that now going forward, with the advent of APFS. In this particular movie, we're going to talk about the Disk Utility program, which is in the Utilities folder. I go to the Go menu, pull down to Utilities, and then double click on Disk Utility to get into it. Disk Utility is just the GUI way to access all of your storage, right? It starts off at the top here, with your internal storage, and then has your external storage down below.
External, these are items that I happen to have connected over USB-3 connections, so these are just external hard drives, plugged in over USB-3. Pretty easy, right? The disk itself is represented in this portion of the outline-like format here, hierarchically, the volume is formatted out and listed below it. Here you can see I've got a five terabyte USB external physical disk, and I've got a volume here and it describes right here that it's an Mac OS extended journal volume. I can see capacity, how much data is used on the disk, what its UNIX device information is, and, you know, other useful information here.
If I want to erase this volume, it's a very handy button that's right up here in this menu bar. All I need to do is give it a name, choose what format I want to use. If I want to use security options in order to erase it, I would choose those, and we're just going to go with fastest, and hit Erase. Of note, with the security options there, if you're erasing an SSD, avoid using the multi-pass erase. You will destroy your SSD, because SSDs age out based on how many times each memory unit's been written to, and besides, there's a lot of research that points to writing over that SSD storage as being ineffectual in erasing it really anyway, so don't do that.
The multi-pass erase idea with physical media is that if you write over the same grooves over and over and over again, you will eliminate the magnetic signatures that represented the old data by writing over that data over and over and over again. So basically, that's it. If we do the simple erase like I just did, all it does is it removes the header information that tells the system where data is on disk, but it doesn't really get rid of it until it's written over later on through using it. So we've just erased this disk, and here you can see, we had a successful operation.
We can get that by clicking down on this disclosure triangle, and it successfully created our five terabyte case-insensitive HFS Plus volume. Great, hit Done, and there we are. If I wanted to do things like partition this, I would need to move up a level in this hierarchy, click the partition button, and then this gives us this new sort of pie graph way of looking at our partitioning. The old method in the old disk utility was more of a bar graph, this is more of a pie graph. You just click the plus button beneath the graph, and then slide around the little knob there to decide how big you want each partition to be.
Pretty straightforward stuff. If you want to create three, you just keep hitting the plus button, until you've got all the partitions that you want, right, and you just keep on going there. Obviously we're not going to do that, I'm going to un-click all of those, and let's just create two partitions, that makes that pretty easy. The second partition will be Data 2, and we'll make both of them Mac OS extended journaled, and here you can see that each one is going to be two and a half terabytes. We click Apply, it tells us it's going to destroy all the data on the drive, and of course that's exactly what you would expect, and the result will of course be two volumes on the desktop.
They look like two external hard drives, but in fact, it'll be one, and this is a great way to separate out different kinds of data. If you wanted to have an operating system on one half, and have pure data on the other half, or maybe you run around with tech disks, and you need to build out systems, and you need to work on lots and lots of computers that have different boot parameters, maybe you want to have a different operating system on each of those partitions. This is how you would accomplish that. Now, it looks like our operation failed here, and it says here that the new size must be different than the existing size.
The new size was different than the existing size, so this is simply a Disk Utility error, and this is, you know, this is part of dealing with a very new-ish version of the operating system. We've got this here and this here, and we failed to rename it. You notice that it did complete the partition process, but it did not rename the partition. Now, of interest here, I can go into the Finder, and I can just select that volume, hit the Return key on my keyboard, and I can rename this volume to what I wanted it to be.
And hit Return again, and that is now renamed, and that name will show up here in Disk Utility with no problem. I'm not super thrilled that there was an error there, so what I'm going to do next is I'm going to run First Aid on both of these volumes. So I'll start with the one that had the failure, and I'm going to click First Aid, and Run, and I'm going to flip down the disclosure triangle to make sure that I know what is going on, and if I see that it says that everything is fine, operation successful, well, I'm going to trust that volume. That should be fine.
And same thing with the Data volume, now I'll run this on that as well. And once again, flipping down the disclosure triangle, and here you can see, everything is just fine again. There we are, that remounts the drive. Now we've got two partitions, you can see that both partitions show up here in our data graph of what's going on with our data. We've now seen how you erase a volume and a disk, we've seen how you partition a disk, how you run First Aid on a disk, all of that information is viewable not only here within the GUI right here, but if you need more data about any of these elements in the left-hand sidebar, you would simply select an item, hit the info button, and a lot of extra information is available for you here, about that device, or about that volume, contextually based upon what you have selected.
Different volume information or device information will show up. So that is a quick run through of what you can do with disk manipulation, storage manipulation, here within Disk Utility.
- Backing up macOS Sierra
- Restoring files
- Managing iCloud
- Working with storage
- Creating Apple File System disk images, containers, and volumes
- Reviewing logs in the console
- Using log commands
- Securing macOS Sierra
- Configuring Sierra via MDM