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jimtron

macrumors member
Original poster
Jul 27, 2008
91
4
I've often heard that Macs don't need to be defragged, but I have a 8tb external usb drive that is getting slow; when I open a folder sometimes I need to wait a few seconds to see the contents (when the drive is mounted and awake). I still have 5tb available on this drive.

At this link I saw this: "Most users, as long as they leave plenty of free space available , and don't work regularly in situations where very large files are written and rewritten, are unlikely to notice the effects of fragmentation on either their files or on the drives free space much."

I have many very large files on this drive, like over 1gb each.

I've run DiskUtility on the drive, and it passes first aid, and I ran DiskWarrior on it as well (the index is efficient according to DW).

Any suggestions on how to optimize this drive?
 

Ben J.

macrumors 65816
Aug 29, 2019
1,074
637
Oslo
So, I assume you don't have the "put drives to sleep" option enabled in system preferences?
 

chown33

Moderator
Staff member
Aug 9, 2009
11,003
8,897
A sea of green
What format is it in? HFS and APFS have an efficient directory structure. None of the FAT formats do (FAT16, FAT32, exFAT).

Another thing that will slow disks down is when they start to fail. The typical failure mode is that the drive needs to read sectors repeatedly, until valid data is returned. This is done by the drive itself, so from the computer's viewpoint, it's just a drive that responds slowly. Or sometimes quickly and sometimes slowly.

Simply having large files isn't going to inevitably cause fragmentation. It's the rewriting that can lead to fragmentation, not simply the existence of a large file. For example, a large movie file that's essentially read-only after being created doesn't lead to fragmentation. Conversely, a large database file that's frequently written, rewritten, expanded, and contracted, might well lead to fragmentation. Or worse, having many large database files that are all being rewritten, expanded, and contracted.
 

jimtron

macrumors member
Original poster
Jul 27, 2008
91
4
So, I assume you don't have the "put drives to sleep" option enabled in system preferences?
Correct. Also, I'm aware that sleeping drives take a bit of time to spin up to speed.

What format is it in? HFS and APFS have an efficient directory structure. None of the FAT formats do (FAT16, FAT32, exFAT).

I believe it's one of the former formats, not FAT. I don't see HFS or APFS anywhere in DiskUtility, it does say GUID and Mac OS Extended (Journaled).

Another thing that will slow disks down is when they start to fail. The typical failure mode is that the drive needs to read sectors repeatedly, until valid data is returned. This is done by the drive itself, so from the computer's viewpoint, it's just a drive that responds slowly. Or sometimes quickly and sometimes slowly.

Simply having large files isn't going to inevitably cause fragmentation. It's the rewriting that can lead to fragmentation, not simply the existence of a large file. For example, a large movie file that's essentially read-only after being created doesn't lead to fragmentation. Conversely, a large database file that's frequently written, rewritten, expanded, and contracted, might well lead to fragmentation. Or worse, having many large database files that are all being rewritten, expanded, and contracted.

Any way to check on whether the drive is failing or not? I've got SMART Reporter app which gives OK status, and like I said in the OP I ran DiskUtility and DiskWarrior...any other tools to check the drive health?

Also, any tools you'd recommend to de-frag the drive?
 

chown33

Moderator
Staff member
Aug 9, 2009
11,003
8,897
A sea of green
I believe it's one of the former formats, not FAT. I don't see HFS or APFS anywhere in DiskUtility, it does say GUID and Mac OS Extended (Journaled).
Mac OS Extended is HFS+. So definitely not a FAT version.

Any way to check on whether the drive is failing or not? I've got SMART Reporter app which gives OK status, and like I said in the OP I ran DiskUtility and DiskWarrior...any other tools to check the drive health?
From what I vaguely recall of SMART Reporter, it requires that the controller in the external drive supports reporting of SMART status. Not all controllers do that, so getting an OK from the app might not be significant, and I don't know what kind of details any other apps might be able to read.

Also, any tools you'd recommend to de-frag the drive?
I've never felt the need to do it, so I've never bothered to look.
 

Fishrrman

macrumors Penryn
Feb 20, 2009
29,279
13,377
Platter-based hard drives used with the Mac routinely require de-fragmentation (regardless of what Apple says about it).

You can use Drive Genius, TechTool Pro, iDefrag (which I believe is now free).

For iDefrag, try the Coriolis software archive here:
 

jimtron

macrumors member
Original poster
Jul 27, 2008
91
4
Platter-based hard drives used with the Mac routinely require de-fragmentation (regardless of what Apple says about it).

You can use Drive Genius, TechTool Pro, iDefrag (which I believe is now free).

For iDefrag, try the Coriolis software archive here:

Will give one of those a try, thanks!
 
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