IMac – Added a 128GB SSD to 27″ iMac

Definitely make the SSD your boot/app disk and set your computer to put hard disks to sleep. But even then there are many factors that can cause the drive to spin up even. Sometimes just getting an open dial box will cause it to spin up.

I'd first make sure your HDD is not shown in the sidebar - if it is there it will definitely spin up every time you get a save or open dialog box or a finder window.

Even after doing that I still had it spinning up more than I wanted so I followed this blog post on Dae’s blog to make an apple script that will unmount or mount it so I can explicitly control when it sleeps or doesn't sleep. Incase the link dies, here is the script. It even does Growl notification:

set myVolumeLabel to "Storage HD"

tell application "GrowlHelperApp"
    set the allNotificationsList to {"Disk mounted", "Disk unmounted"}

    register as application "Disk Mounter" all notifications allNotificationsList default notifications allNotificationsList icon of application "Disk Utility.app"
end tell

tell application "Finder"
    set diskDev to do shell script "diskutil list | grep \"" & myVolumeLabel & "\" | grep -o 'disk[0-9]*' "
    if not (disk myVolumeLabel exists) then
        do shell script "diskutil mountDisk " & diskDev
        tell application "GrowlHelperApp" to notify with name "Disk mounted" title "Volume mounted" description "Disk “" & diskDev & "” with volume “" & myVolumeLabel & "” has been successfully mounted." application name "Disk Mounter" icon of application "Disk Utility.app"
    else
        do shell script "diskutil unmountDisk " & diskDev
        tell application "GrowlHelperApp" to notify with name "Disk unmounted" title "Disk unmounted" description "Disk “" & diskDev & "” with volume “" & myVolumeLabel & "” has been successfully unmounted." application name "Disk Mounter" icon of application "Disk Utility.app"
    end if
end tell

One thing to note - this unmounts ("ejects") an entire drive - not just a single partition.

The easiest way would have been to create a time machine backup before replacing the drive, then use Migration Assistant to import your account, apps, etc.

However since you replaced the drive already, you will need to get an USB to sata connector, or external enclosure, to connect the old drive in order to access the data.

At this point you have 2 options

1 - Run migration assistant and point it to the external drive. It should see your old account and allow you to import everything. (Sometimes this fails, see http://www.hardturm.ch/luz/2014/02/fixing-os-x-10-9-mavericks-migration-from-external-volume/)

2 - Manually copy the data, or the entire account folder. The original account will be under the /Users folder on the old drive. You can copy the full account if you wish, then use system preferences to create a new account with the same shortname; it will prompt if wish to use this existing folder for the new user account. However, if you decide to try to copy manually you may run into permissions issues. You most likely will have to reset permissions on the folders/files but you can use BatCHMOD to do this (free). Be warned that I would not mess with permissions on the original drive in case of a problem, only work on the copies you make.