12 Replies Latest reply: Sep 17, 2008 7:13 PM by PJGNC
PJGNC Level 1 Level 1 (0 points)
I just connected a WD My Book 1TB ext drive to my I-Mac. I noted that the volume is formatted as extended (journaled). I noticed in some other threads that these drives come formatted as extended (case-sensitive, journaled). Which is best?

Also, Time Machine did not offer to format the drive. There is about 65MB of preloaded stuff on it. Should I remove it?

Thanks for the help!
-Paul (North Carolina)

I-Mac 24, Mac OS X (10.5.4)
  • Scott Radloff Level 6 Level 6 (14,490 points)
    Paul,

    Is this a Mybook "Studio?" Hmmm, I wasn't aware that these came pre-formatted as case-sensitive. Then again, I wouldn't expect them to be journaled, either. Just goes to show how much I know

    For use with Time Machine, a volume must be formatted as "Mac OS Extended (journaled)." It should never be case-sensitive. Notice that I say "volume." The drive, itself, needs to be using the "GUID" partition scheme for an Intel Mac, and the "APM" partition scheme for a PPC Mac.

    Probably, you'll need to format (or partition) the drive. My guess would be that it is using either the "APM" scheme, or worse, the Windows-centric "MBR" scheme (which would render it completely useless for Time Machine). At the very least, you'll need to format the volume to get rid of the case-sensitivity.

    In other words, it would be prudent to copy the data off of the drive. That said, the software you will find "pre-loaded" on the drive is pretty useless in Leopard, IMO.

    Scott
  • PJGNC Level 1 Level 1 (0 points)
    Scott,

    Many thanks for the reply. I am new to Mac and need all the help I can get. Regarding your reply, let me clarify a couple of things...

    The drive is a Mybook Studio I purchased from an Apple Store. It was pre-formatted as extended (journaled) NOT case sensitive. The only reason I mentioned case sens is that I saw in another thread in this forum that someone had a similar volume that was case sensitive. I understand from your posting that I want the volume to be just extended (journaled). Is this correct?

    Also, regarding the drive itself, mine is listed as APM. I do have an Intel Mac (Core2Duo). Given this, do I need to reformat it as GUID or is it OK as APM?

    Thanks again,

    Paul
  • nerowolfe Level 6 Level 6 (13,070 points)
    PJGNC wrote:


    Also, regarding the drive itself, mine is listed as APM. I do have an Intel Mac (Core2Duo). Given this, do I need to reformat it as GUID or is it OK as APM?


    You need to change it to GUID for it to properly work on an Intel box.
    And as mentioned, stay away from case-sensitive file systems in general. I have used them on old Unix mainframes and I have used them on some Linux boxes, but not recently, and I don't miss anything except the complications.
  • Scott Radloff Level 6 Level 6 (14,490 points)
    Paul,

    As Nerowolfe stated, you'll need to change the partition scheme from APM to GUID. This can be accomplished by formatting or by partitioning. Since this is a 1 TB drive (right?), you might want to partition it with 2 volumes: One for use with Time Machine, and one to use as you see fit for additional storage. The partition scheme is chosen in the "Options.." dialogue of the partition tab in Disk Utility.

    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.

    Scott
  • PJGNC Level 1 Level 1 (0 points)
    Scott,

    Thanks again for the info. Just curious, not trying to be a pest...
    Time machine seems to be working OK with it as APM. Why is it better with GUID?
    Also, regarding split partitions, is that really necessary since my main I-Mac is GUID? Wouldn't it be "best" to have the whole 1TB as GUID? And, I have read that Time Machine prefers to have roughly 2x the space of the main system drive. Since my I-Mac as 500GB, I purchased the 1TB for Time Machine. Was this a waste?

    Thanks,
    Paul
  • PJGNC Level 1 Level 1 (0 points)
    Nerowolfe,

    Thank you for the reply and your time. I posted a reply to Scott's last post. Please check it out and let me know of any input. I greatly appreciate the help!

    -Paul
  • Bert Sierra Level 2 Level 2 (285 points)
    I fully agree that you want to keep your Time Machine Volume HFS+ (Journaled and case insensitive). You're likely to get both subtle and obvious issues if you use any case sensitive HFS+ format.

    However, I disagree with the statement about the need for GUID partitioning. This is not needed for removable drives such as Firewire or USB drives, even if you're going to boot off them. To make your Firewire / USB drives compatible with both Intel- and PPC-based Macs, use APM partitioning, and then make your Time Machine volume HFS+ (Journaled, case insensitive). Make all internal drives on Intel machines GUID-based.
  • Scott Radloff Level 6 Level 6 (14,490 points)
    Paul,

    Time Machine will eventually fail in backing up an Intel machine to an APM-scheme drive. If the backup doesn't fail, the ability to perform a "full restore" certainly will. The pertinent information from kbase article TS1550 is this:

    Select a new partition scheme:
    Use Apple Partition Map partition scheme if the disk will be used with Time Machine and a PowerPC-based Mac.
    Use GUID partition scheme if the disk will be used with Time Machine and a Intel-based Mac.


    This is a direct quote from the article.

    Scott
  • PJGNC Level 1 Level 1 (0 points)
    I believe that Scott is correct, especially with regard to bootable. I read in an article from apple that to do a bootable partition on an intel system, it needs to be GUID.
  • Bert Sierra Level 2 Level 2 (285 points)
    OK --

    Looks like you're right about Time Machine needing to see a GUID-based drive when used with Intel machines. My general experience with Firewire drives has been that APM-based drives work fine with both PPC Macs and Intel Macs, but there may be some touchy things about Time Machine which plays a role.
  • Bert Sierra Level 2 Level 2 (285 points)
    My understanding about APS vs. GUID where booting Macs is concerned is this:

    You need to have a GUID-based destination when running the OS X installer on Intel machines. You need to have an APS-based destination when running the OS X installer on PPC machines. However, once OS X has been installed, you can copy the system from a GUID partition to an APS partition and it can be used to boot the machine. We have a number of Firewire drives with APS partitioning that contain both Intel and PPC booting systems, either copies of various DVDs, or hand-built loads that we use for a variety of purposes.

    I wasn't describing things quite right: it's not a matter of the drive being fixed or removable, it's just that I tend to have systems with bootable internal system+user drives and removable external data drives. To keep things simple, the internal drive wants to be GUID-based on Intel machines (so that you can install systems on to it) and the external drive wants to be APS-based on all machines (so that you can plug it in to any Mac). Time Machine, however, may be an exception to the rule; it looks like it requires GUID partitioning on Intel Macs.

    The issue of APS and GUID where booting Leopard is concerned is discussed here: http://www.tidbits.com/webx?14@@.3c7e511e/8
  • PJGNC Level 1 Level 1 (0 points)
    Bert,

    Many thanks for the clarification.