Choosing an external hard drive for back up

Question

This is more for general advice than a specific question. Right now I have my hard drive partitioned and use the second as a backup with Time Machine. It will work for most situations but not all, such as a home fire or break-in (all my photos and music, lost forever!).
What I want to do is buy an external hard drive for backup and keep it at work. I would then bring it home every few weeks to update, but otherwise not store it in the same place as my computer. That way I would never lose more than a few weeks worth of stuff. So, a few questions, the nature of which will let you know how much of a novice I am at this.
1) Right now, Time Machine automatically updates once per hour. When I am using the external drive will I be able to set Time Machine up to only update my back up files when I connect the external drive. Is this difficult.
2) Any suggestions on what kind of external hard drive I should buy, or what features I should look for would be appreciated. I live in a remote area, so something I can get from futureshop.ca would be preferable.
3) My hard drive is about 280 GB. What size should I buy.
Advice on any of the above would be appreciated. Also feel free to toss in anything else you think I should know or consider.
Rgds
PF

Answer 1

Snowfog wrote:
This is more for general advice than a specific question. Right now I have my hard drive partitioned and use the second as a backup with Time Machine. It will work for most situations but not all, such as a home fire or break-in (all my photos and music, lost forever!).
What I want to do is buy an external hard drive for backup and keep it at work. I would then bring it home every few weeks to update, but otherwise not store it in the same place as my computer. That way I would never lose more than a few weeks worth of stuff. So, a few questions, the nature of which will let you know how much of a novice I am at this.
1) Right now, Time Machine automatically updates once per hour. When I am using the external drive will I be able to set Time Machine up to only update my back up files when I connect the external drive.
This is what I am currently doing among 3 different backup disks (1 Time Capsule, a WD500GB, and a Lacie 160GB). You won't have to "set" anything up other than attach the new drive and select it in the TM prefs. Then when your done, reselect your normal TM disk.
2) Any suggestions on what kind of external hard drive I should buy, or what features I should look for would be appreciated. I live in a remote area, so something I can get from futureshop.ca would be preferable.
Most any drive will do, as you partition it correctly to begin with.
*_How Should a Time Machine Hard Disk be Prepared?_*
For Time Machine to work properly, the hard disk must be formatted “Mac OS Extended (Journaled)” and its’ Partition Scheme should be either GUID or Apple Partition Map.
Time Machine is incompatible with disks partitioned as Master Boot Record (MBR). Unfortunately, this describes nearly every hard drive you can buy because MBR is a Windows partition scheme. (Naturally, this DOES NOT apply to Apples’ Time Capsule.)
For some, Time Machine begins to perform as expected with a new external hard disk. But then the initial full backup or subsequent incremental backups fail. The user only later discovers the hard disk was still partitioned as Master Boot Record (MBR).
One article on Time Machine made this observation: “Virtually everybody will have to open Disk Utility and repartition the disk as APM or GUID. It doesn't really matter which one because the Time Machine disk will not be bootable anyway. APM allows a disk to boot a PowerPC, GUID allows the disk to boot an Intel processor but both are easily digestible by Time Machine on either kind of processor.” [http://www.girr.org/mac_stuff/backups.html]
It’s been recommended by many here that your reserve +at least+ double the size of your primary hard disk, that way Time Machine backups have room to grow as the size of your data grows. Additionally, the more space you give Time Machine the more history it can preserve. The less space you reserve for Time Machine the sooner older backups & deleted items will disappear.
One poster recommended this regarding multiple partitions: “If you do create multiple partitions (half and half would be a good place to start), make sure you use the first partition for Time Machine, and the second for your own stuff (the first one will be on top in the graphical representation shown in Disk Utility; you'll understand when you see the partition tab). This way, you can expand the Time Machine volume at any later time by deleting the second partition. Disk Utility allows this dynamic re-sizing of volumes, but volumes can only be expanded toward the end of the drive, when a volume that comes after is deleted to create the room.” [http://discussions.apple.com/thread.jspa?threadID=1712437&tstart=0]
Procedure
Connect the hard disk you wish to use for Time Machine backups.
Launch Disk Utility.
It will appear twice in the pane on the left. (Make sure you recognize that it is different from the 2 icons that represent your Macs' internal drive.) The upper entry represent the device as a whole, including the controller inside. The lower entry represents the hard disk contained within the device.
Click on the upper icon of the external hard disk.
Select the "Partition" tab.
For "Volume Scheme" choose "1 partition". (Choose 2 partitions if you intend on storing other data on the disk besides your Time Machine backups. Ensure that the two partitions have different names.)
Name the disk.
Format should be "Mac OS Extended (Journaled)".
Click "Options".
Select either GUID or Apple Partition Map. (See above for significance)
Click "OK".
Click "Apply". Then click “Partition”.
Once the external hard disk is repartitioned, select it again in Time Machine preferences and use it for your backups. If you chose to create 2 partitions, then select the first partition for Time Machine backups, and the second for additional files/folders.
3) My hard drive is about 280 GB. What size should I buy.
Any TM backup drive should be +at least+ twice as large as your Macs internal hard disk.
Let us know if this resolves your issue.
Cheers!