Can I plug my 2nd 2tb WD HD into my first one?

Discussion in 'Mac Basics and Help' started by pb1300, Apr 24, 2010.

  1. pb1300 macrumors 6502a

    Joined:
    Feb 29, 2008
    Location:
    Aigio, Greece
    #1
    I just received my second Western Digital 2Tb hard drive, and I was wondering if I can plug it into my other one, via firewire? I notice that they have two FW ports on the back, so I was thinking that it was possible. Am I right? If so, are there any additional steps I need to take in order for the computer to see I have 4tb of external HD space? Thanks.
     
  2. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #2
    Doubt it. You could create a RAID 0 array with Disk Utility, I think, then they would be seen as one 4TB HD
     
  3. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #3
    You can plug up to 63 Firewire devices onto one Firewire bus, including HDDs. So you can at least daisy chain them and see them as two separate drives. A RAID would only add instability. If you want to go for speed FW800 is not the best way anyway with current S-ATA HDDs.
     
  4. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #4
    But can the HD act like a hub? I think the second port is for multiple computers so you can plug it into two computers at the same time, not for another HD
     
  5. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #5
    If we talk about Firewire, then yes, it acts like a "hub".

    You have FW HDD 1 with two firewire ports, so you use one to connect it to the computer, the other to connect another FW HDD 2, which has two FW ports to connect another FW HDD 3 to it and so forth. At work we currently have five to eight FW800 HDDs connected on one chain, three chains in all.

    Also connecting two computers via FW allows for them to network, but I never got two Macs to recognize one FW HDD which was in between the chain.
     
  6. Hellhammer Moderator

    Hellhammer

    Staff Member

    Joined:
    Dec 10, 2008
    Location:
    Finland
    #6
    Ahh, okay, thanks for clearing that. But it still shows up as two 2TBs, right? To show them as one 4TB you would need to RAID them?
     
  7. spinnerlys Guest

    spinnerlys

    Joined:
    Sep 7, 2008
    Location:
    forlod bygningen
    #7
    Yes, two 2TB HDDs will show up as two 2TB HDDs in Disk Utility and in as many volumes (partitions) the HDDs is split into in Finder.

    To see them as one 4TB volume, one would need to use RAID, for which there are plenty of enclosures to do so.
     
  8. pb1300 thread starter macrumors 6502a

    Joined:
    Feb 29, 2008
    Location:
    Aigio, Greece
    #8
    Thanks for the quick responses! Im going to use the first one for my itunes and iphoto library, so I can wirelesly connect to my MB and :apple: TV. The second I want to use for backups.

    Another question, more of an electrical one now. Can I use the one power source to power both HDs? What I mean is can I splice into the one power source and have two outputs to the two HDs?
     
  9. ahankinson macrumors member

    Joined:
    Feb 1, 2010
    #9
    You can't mount the same disk on two computers without using a network connection like NFS, SMB or AFP. They'll run into all sorts of file locking problems.

    By stripe RAIDing them together, you're essentially halving your reliability. If one drive goes, you lose all of your data. If you keep backups of the whole thing you'll be OK, but a better idea would be to mirror RAID them and have built-in redundancy.

    I would definitely not mess with the power. The big black box on your electrical connection is tuned to work with one enclosure. Increasing the load on that will, at the very least, risk electrical damage to your components. In the worst case, though, it will be a fire hazard, since the components in the adapter are likely not designed to handle double the load and may melt or overheat.
     
  10. pb1300 thread starter macrumors 6502a

    Joined:
    Feb 29, 2008
    Location:
    Aigio, Greece
    #10
    OK, so definitely NO to the power thing, lol. It was just a thought.

    As far as the bolded part is concerned, can you just go into a little detail into what that means? And how would I go about doing what you said? Like I said earlier, I want one for a backup, and the other for itunes, iphoto, and some other storage.
     
  11. BlueRevolution macrumors 603

    BlueRevolution

    Joined:
    Jul 26, 2004
    Location:
    Montreal, QC
    #11
    I would not recommend messing with RAID at all with external hard drives.

    1) RAID is not a backup solution.
    2) RAID is considerably faster than JBOD, but since everything is going through the same 400 Mbps straw, it doesn't matter.
    3) Using one drive without the other isn't an option if you set up a RAID.
    4) With RAID 1 you get half the space, with RAID 0 you get half the reliability. Neither is a good idea for you.
     
  12. old-wiz macrumors G3

    Joined:
    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #12
    The second port is for daisy chaining only. Two computers accessing one hard drive would result in disk corruption. Both computers would try to update at the same time and it would cause a massive mess.
     
  13. old-wiz macrumors G3

    Joined:
    Mar 26, 2008
    Location:
    West Suburban Boston Ma
    #13
    Exactly my point. I worked in OS internals before I retired and know full well the issues of file locking, as well as volume locking.
     

Share This Page