Common SSD Pitfalls

For the last year, I’ve been using an OC-Z Vertex 2 as my primary drive. As you are probably already aware, they are quite fast. Even larger applications rarely take more than a single bounce in the Dock before they are finished loading, and you hardly ever notice when you run out of physical RAM and start swapping to disk.

Unfortunately, due to being relatively immature and expensive when compared to hard drives, an ideal setup can be difficult to attain. Due to limitations in the MacBook hardware and/or Mac OS itself, this is especially true when you are using a third-party kit to replace your optical drive with a second drive bay. Here are some issues I’ve run into over the last year, and how I’ve worked around them.

Using an OptiBay

There are quite a few caveats with using a second drive:

  • Safe sleep only works properly if you install Mac OS on the drive located in the normal hard drive bay.
  • The sudden motion sensor only protects the normal hard drive bay.
  • Placing a hard drive in the OptiBay is going to result in more noise than the rubber mounts Apple provides for the normal hard drive bay.
  • Apple’s DVD Player app only works when the superdrive is connected internally, not via a USB enclosure.

To net the maximum benefit of an SSD, you really want to install your OS and applications on it. Coupled with the fact that I consider safe sleep to be a necessity, I was left with little choice but to stuff my SSD into the hard drive bay.

To attempt to minimize risk of damage to my hard drive, as well as reduce noise, I was able to use the pmset tool to force disks to sleep after 1 minute of inactivity:

sudo pmset -a disksleep 1

For good measure, I also disabled the sudden motion sensor. This isn’t strictly necessary, but it’s simply not necessary to leave it enabled for an SSD.

sudo pmset -a sms 0

Trouble waking from safe sleep

After swapped my solid state into a new 2011 MacBook Pro, I eventually noticed that my computer would no longer successfully wake from safe sleep. After trying lots of different things, I had narrowed it down to a possible firmware issue. Upgrading it was an adventure in misfortune:

  • The firmware upgrade tools are for Windows and Linux only.
  • The MacBook Pro didn’t want to boot any OS that wasn’t Mac OS off USB – only the internal superdrive, which I had removed.
  • Thanks to this, the only way to get Windows installed would have been to remove my SSD, reinstall the superdrive, install Mac OS on my hard drive, install Windows via Boot Camp, put the SSD in the optibay, and finally boot into Windows.
  • I don’t have any desktops available

I was able to eventually do this using my old MacBook, and it did fix the problem. It wasn’t an ideal way to spend a Saturday afternoon.

TRIM and other tips

Depending on the chipset powering your SSD, enabling TRIM support will have varying amounts of impact. It’s not strictly necessary for SandForce-based SSDs like my own, but it may give you peace of mind.

I’ve also read some people suggest doing things like completely disabling safe sleep or otherwise going out of their way to avoid writing data to the SSD unnecessarily. It’s true that writing wears out flash memory, but, theoretically, you would need to write hundreds of gigabytes of data every day for years to a typical SSD before you would ever run into problem with wearing.