With 1.7TB of data, my 2TB Time Machine backup volume has been feeling squeezed for space, even though I had excluded various items that are more archival in nature (and for which I have other backups). Time Machine keeps copies of both deleted files and versions of files as well, so a good rule of thumb is 50% - 100% more space than what is to be backed up.
Here’s what I did and what you can do:
- Make sure you have an up-to-date Time Machine backup.
- Removed the Time Machine drive(s) and set aside as a backup.
- Install new drive(s).
- Initialize the new drive(s), set up RAID if you’re using that (I set up dual 2TB drives as a 4TB RAID-0 striped volume “tm”).
- Set Time Machine to backup to the new volume, then let it chug away until done.
You don’t have to use a RAID-0 stripe; you might want a single drive or a RAID-1 mirror instead.
But I needed more than 2TB space, and I like the double speed that the striped pair of drives offers— and it stays faster as the volume fills.
Get more space than you need, because drives slow down as they fill up.
Here’s how to set up RAID.
Here’s how to partition a drive.
For a dual-drive RAID-0 stripe for Time Machine, I like the FirmTek 2ME2-E. For eSATA, you’ll also need a card for your Mac Pro or MacBook Pro (only certain models of MBP have the required slot). Here’s a cart with the various parts I used or recommend.