MacBook Pro is *slow* when I back up with Time Machine

January 27, 2015 9:28 PM

I have a 2-year-old MacBook Pro with a 500 GB SSD running Yosemite. It was fine until 3 days ago, when the computer slowed to a crawl. I rebooted several times; each time, it got slow again. I eventually realized that it slowed down when trying to back up to the external hard drive. I ran Disk Utility, which found no errors on the SSD or the external hard drive.

I took the laptop to the Apple Store today. They ran diagnostic software (not Disk Utility), and it indicated that my volume was corrupt and needed to be repaired. They recommended that the disk be wiped. I didn't want to do that, since the laptop is my work machine and I'm trying to finish a project in the next week. I asked the 'genius' to run Disk Utility, and it also said the volume was corrupt. I took the laptop home to think things over. I ran Disk Utility at home and it found no errors on the hard drive.

I'm confused by these contradictory results. The only real problem is that my laptop isn't getting backed up now (except for some files to Dropbox). MeFites, please hope me!

posted by lukemeister to Computers & Internet (6 answers total)

Disk Utility is able to do a more thorough check when you're not booted from the drive it's checking - this may explain the contradictory check results. Also, did they actually run a Disk Utility repair while you were there? I'd certainly hope so.

The only real problem is that my laptop isn't getting backed up now

Well, that AND you appear to have filesystem corruption which could render your laptop unusable at any time. Seriously, just because it appears to be working fine-ish now doesn't mean that it'll continue to do so until your project is complete.

I'd recommend making sure you have a full backup of everything you can't afford to lose, then boot from the recovery partition and confirm that Disk Utility reckons the drive is OK. I'd also run DiskWarrior over it, but that's a commercial product and you'll have to wait for them to ship you the bootable USB stick. (Seriously, buy DiskWarrior. It's able to recover corrupted disks where Disk Utility just throws its hands up and goes "oh well, I hope you didn't really need any of that because it's all gone").

Depending how much corruption Disk Utility and/or DiskWarrior find, a nuke and reinstall may be your best bet in the end. If you decide to put it off until your project is finished, just remember that the gods of bad timing may well schedule it for you at the most inconvenient moment.
posted by russm at 9:48 PM on January 27, 2015 [2 favorites]

Is this an aftermarket SSD, or one that came from the factory?
posted by palionex at 12:16 AM on January 28, 2015

Firstly, it could be the external HD that's the culprit. Eject/unplug the Time Machine HD and use your computer as normal - disable Time Machine temporarily. Do a few CPU-intensive tasks and then stop; see if your computer works normally. If so, it's the external HD. Solution? Try erasing the HD then starting over. Con? You'll lose all backups (and any data on your HD, so check accordingly first!).

If the OS still feels sluggish/slow with Time Machine disabled, and the external HD unplugged, I'd try booting to Safe Mode first. This will rule out any odd user/OS-related issues. If your MBP seems to be working better in Safe Mode, it may be corrupted permissions. If that's the case, open Disk Utility and repair permissions. To be completely safe, I'd also boot to the Recovery Partition (press CMD+R when turning on your computer), click Utilities on the menu bar, then Terminal, then type resetpassword. Press Enter. You'll then see on the bottom of the dialog that comes up; reset home directory permissions and ACLs. Do that. Reboot.

If the same issues pop up in Safe Mode, then onwards to the next step:

What I'd recommend you do:

a) Move all your files to Dropbox. Post haste. Buy storage if you need to. As a backup, drag your files/apps to an external hard drive.

b) Download the latest version of Yosemite (10.10.2 as of this writing) from the App Store (it'll ask you if you want to re-download Yosemite - click Continue). Follow the instructions here to create a bootable installer (so you don't have to re-download Yosemite later) on an external hard drive.

c) Fun part: do a fresh install of OS X. Boot to the bootable installer (open System Preferences > Startup Disk, select the installer HD, then reboot), click Disk Utility. Erase your HD completely. Go back to the main screen; click Reinstall OS X. Follow the instructions, let the installer do its' thing, then set everything up.

If, after all that labor, it still slows down, it's definitely your SSD. In that case, time for a replacement, unfortunately.

Hope my instructions and suggestions were clear as mud. Please memail me if you've got any questions or need clarification!
posted by dubious_dude at 12:40 AM on January 28, 2015 [3 favorites]

If your SSD is aftermarket and nearly full then it could be the culprit. Get thee TRIM Enabler.
posted by neckro23 at 10:32 AM on January 28, 2015

Response by poster: Thanks for the info! Ran Disk Utility in Recovery Mode last night. Both SSD and external HD had no problems (or so it said). SSD is original from Apple, not aftermarket. Time Machine backup gets stuck after "300 bytes of 2 GB" or so.
posted by lukemeister at 10:39 AM on January 28, 2015

Get thee TRIM Enabler.

"Make sure to read this before using Trim Enabler on OS X Yosemite” (from the Cindori web site).

The gist is that Yosemite disables trim on third party SSDs, and that re-enabling support involves turning off kext signing security, which you may want not to do.
posted by Quinbus Flestrin at 9:58 AM on January 29, 2015