I installed a new 115GB SSD with a clean lion install in my MacBook pro (2010) with the data doubler containing my old seagate hdd.

The install took over five hours, which made me pretty suspicious to begin with.

But now I'm seeing why: every 30 seconds or so, whatever app is using the disk seems to completely freeze.


Chrome accessing cache

App store downloading Xcode

Sublime text saving a file

Safari doing anything

Dropbox sync

I've turned off hard drive sleeping, which helped a bit but the benefits appear to be gone. I've also switched te hibernate mode to kill the image and disabled spotlight. The only general solutions google has suggested that I have yet to do are turn on TRIM (which OWC does not recommend for their drive) and add the noatime mount option.

I'm doing a permissions repair now, but I could use more suggestions.

Fs_usage and logs don't show anything that catches the eye.

4 Answers 4


I've got a OWC Mercury 115GB in my MacBook (2007) and encounter the same problem although never as severe as you describe. It was fairly frequent (multiple times an hour) while I was running FileVault2 but once I turned it off, it became much less frequent (perhaps once an hour). Normally, I see a complete freeze of the system, not just the application, for about 30 seconds.

SSD garbage collection seems like a likely suspect. In theory, the Sandforce controller plus the larger scratch pool on the OWC drive makes TRIM unneeded but if GC is the issue, maybe TRIM would reduce the frequency. That said, I read lots of reports of people seeing a similar problem when they hacked their system to support TRIM with 3rd-party SSD's under Snow Leopard. I stopped following the discussion when I upgraded to Lion so I don't know anything about current experiences.

I try to keep at least 30GB free.

5+ hours seems like a crazy long time to do a Lion install so maybe you have a different problem.

  • 1
    I updated the firmware following the instructions on the OWC site and the problem seems to have gone away. Nov 12, 2011 at 21:36

I wonder why did you put HDD in optical bay. It has no advantage to it whatsoever. On the contrary you loose SMS for HDD and have to turn it off for SSD.

By the way the last thing could possibly cause such problems.

  • I tested this atomically. not an issue. As for why, I wanted to continue using my nice big harddrive and had no use for an optical drive.
    – Oren Mazor
    Dec 7, 2011 at 7:20
  • @OrenMazor I mean that it's more appropriate for your model to jut put SSD into optical bay caddy and leave HDD where it originally was.
    – iskra
    Dec 7, 2011 at 13:07
  • as far as I know, that would mean I can't run my OS off the SSD
    – Oren Mazor
    Dec 7, 2011 at 15:48
  • No you can. That statement only applies to PATA to SATA optical bay convertors (because of sleep/hibernate problems with those). SATA to SATA is fine.
    – iskra
    Dec 7, 2011 at 20:13

So, after trying to ignore the problem for a long time, I switched my HDD and my SSD, so my HDD is in the main harddrive channel (where it started) and the SSD is where the optical drive goes.

lo and behold, it works. I avoided doing this because I remember at one point you could not have your main OS drive be in the optical drive channel, yet it works. and works beautifully.

so clearly the problem is as suspected with apples SATA3 support on that main harddrive channel.


I have freezes on Corsair SSD (SandForce based) a few times per day on Snow Leopard. One things is helped - is a updating SSD firmware to version 5.0.3. Its not easy and may be danger — but in my case its resolve problem on 100% — freezes is totally gone.

I dont have Windows on my Mac Mini - and I use this instructions for updating SSD firmware http://forum.corsair.com/v3/showpost.php?p=635915&postcount=31 and its worked.

  • Can you please add some details about the steps required to update the firmware of your specific SSD model?
    – nohillside
    Apr 18, 2013 at 15:45

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