Hard Disk Drive Replacement Options

The way I found out about it was when I noticed that at boot up, the Performance Probe tool that came with Scannerz was always running a few hundred megabytes more than it was without it. I built a Fusion drive some time ago, more or less just to play with it when I first noticed this. I keep clones on regular backup drive and when I booted off the clone, right after the system started up with no applications running, just the OS, the used memory was always about 400MB more. Interestingly, if you boot off the clone and the Fusion is still connected, that same overhead seems to be gone. I'm reporting this more or less from memory so my recollections may not be 100%. You might want to search the web and see if you can find something a little more specific about it instead of my recollections from over a year ago.

I can't imagine the overhead has gotten any better. The trend seems to be the opposite.

Now that you've tried a Fusion maybe you should reformat and try the split drive approach to see which one you like better.

I would check out crucial memory and make sure you back up your drive as soon as possible. Go to www.crucialmemory.com, download their system scanner, and it will bring you to hard drives and RAM kits compatible with your machine. But before you do anything, take it to a Genius Bar to have them look it over to see what you need replaced. My last macbook did need quite a lot of service shortly after purchasing it brand new. One problem was the hard drive. I don't know if you would experience the same symptoms, but it would gradually get slower and slower throughout the day. Eventually, disk utility wouldn't be able to repair the drive and tell me to back up as much data as I could but by then, it was too late but thankfully I have a 2TB Time Capsule. From there, it wouldn't finish booting up. Another situation, I had experienced the same symptoms but slightly different. It would slow down but stop at a certain point and disk utility wouldn't detect any issues.

I've ordered from crucial in the past and I'm very satisfied with their products. So far, I haven't had to send anything back to them. They're relatively cheap and perform very well. Good luck!

MrWilliams201:

It sounds like that would work, just make sure that anything the OS or its apps write to isn't cross linked. For example, Mail data is in the users Library->Mail folder. If that was linked to both Mavericks and Snow Leopard, which would imply you separated then aliased the Users folder itself, I think Mavericks would take that mail from Snow Leopard and import it to a new format. I don't know if it would destroy existing Mail in the process. That's the sort of thing you need to be careful about. Lots of apps write to the Library directory.

Out of curiosity, how's that working out with newer operating systems. Snow Leopard can't even seem to see El Capitan from System Preferences when I try to set a new boot target. I have to reboot, hold down the alt key and then select the El Capitan partition from the menu, then after booting in use System Preferences to set El Capitan to the boot drive.

If someone knows a better way to do this or there's some tool available, like some of those boot managers you can use with Windows and Linux, to do it I'd love to know about it.

Correction/clarification to my above post. Snow Leopard won't see a Core Storage partition connected to the unit. CS is now, apparently the default.

If you hate the Core Storage business, you can re-initialize the drive under an older Mac OS X and walk away from core storage.

There is also a procedure that will let you delete the Core Storage added partitions, but it is done in Terminal without a net. One false move and your other drive could be gone.

Core Storage doesn't bother me that much, although I'm not certain making it a default in an install without letting users know about it is a good idea.

When I first installed Yosemite, it was put on a partition that was already formatted the old way, so it went on without changing the drive's partition. When I installed El Capitan beta it was put on a new drive without anything on it so by default (and without warning) it installed it as Core Storage. When the El Capitan partition wouldn't show up on Snow Leopard I assumed Snow Leopard couldn't see El Capitan. Later, when I installed El Capitan on another regularly formatted drive, it appeared to the Snow Leopard partition.

For anyone interested, and feel free to correct me if any of this is wrong, here are some rules about Core Storage I've discovered:

1. Core Storage volumes won't be seen or accessible by Snow Leopard or earlier. You can see such a drive in the command line version of disk utility, but won't be able to do much with it.

2. Although Lion can see Core Storage, it seems to have trouble making sense of a Fusion Drive.

3. Mountain Lion can see all Core Storage including Fusion drives, but it can't fully manipulate files on El Capitan or Yosemite. If you have a multi boot system or perhaps you've booted from a Mountain Lion based system to service or work on someone else's unit, attempts to read some files on and El Capitan or Yosemite based system will fail because the type of compression used in the resource forks of the file system on the newer OS versions is not understood. In fact, if you're working in a command line shell it will notify you of an I/O error which may lead people to think that the hard drive has problems when in fact it's failing to read because it can't understand the new types of compression used on Yosemite and El Capitan. The resource fork compression is NOT part of Core Storage, it will be a problem to earlier OS versions whether the drive is partitioned as non-Core Storage or Core Storage.

4. Mavericks can, at least to the best of my knowledge, see it all. El Capitan and Yosemite can manipulate any files on earlier OS versions without a problem.

I hope this helps anyone interested.

Core Storage Volumes are needed for FileVault 2 encryption, and for building a Fusion Drive. At this writing, it can be removed with impunity if you are not doing either of those things with your drive(s).

It does it on Mountain Lion too.

ThomasB2010-

When you ERASE a drive over 2.2TB in ain Internal Drive bay, it is given the Logical Volume stuff in Mac OS X 10.8.3 and later. Many readers here considered that a BUG. Logical Volume Group partitions were not needed, and interfered with re-ERASE and other functions. There are several wildly different work arounds:

• Re-ERASE in an external enclosure, provided yours can accommodate drives over 2.2TB (really old ones can not).

• Re-ERASE using Mac OS X or Recovery_HD or Installer the predates 10.8.3

• Manually delete the Logical Volume group partitions using Terminal.

MrWilliams201 wrote:

Thank you all. A surprising amount of insightful input indeed!

Here are some follow on questions:

1. Would it be a good idea to order a new SATA cable anyway? Mine apparently still works but I'd be fearful it might not be after working with it. If they can be as problematic as some say, maybe having a spare around wouldn't be such a bad idea anyway.

2. If I decide on an SSD/HD combo and pull the optical drive, is the data doubler really needed? I have an old busted OD and was thinking I could strip the contents out of the case and build some brackets to secure and HDD or SSD inside it. Does the data doubler do anything else other than act as a frame for the HDD/SSD so it can be securely held inside a unit?

3. Regarding cables, I read somewhere that some SATA cables are limited to 3GB/s but others are for 6GB/s. Is that true, and how can I tell the difference? MacTracker shows mine as have a 3.0Gb/s interface, but If I used a different cable, could it be a 6 Gb/sec interface? Is the speed limited by the cable or the logic board itself?

For future reference, here's the specs on my model

MacBook Pro (13-inch, Mid 2009)

Identifier: MacBook Pro 5,5

Model Number: A1278

Thank you all again.

1. Yes (budget for it) and be prepared if it boots externally but not internally, buy one.

2. You're on you're own thare

3. Buy a SAT3 cable (6Gb/s interface)