can you put the boot disk as an external?

Discussion in 'Mac Pro' started by j2048b, Jun 17, 2009.

  1. j2048b macrumors 6502a

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    #1
    I have an 08 mac dual quad and wanted to ask if i could boot my computer from an external instead of having the disc as an internal?

    that way i can use the 4 bays for terra byte action and run a raid of sorts without having one bay for the OS.

    any help?

    also if i can do this could i also install boot camp on another external to run my boot camp partition from an external as well?

    or can you run parallels or fusion from the same disc as the mac OS at the same time?

    thanks
     
  2. Consultant macrumors G5

    Consultant

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    Jun 27, 2007
    #2
    Yes video people do that with external firewire 800 boot disk.

    You can boot from either usb or firewire, but you should use firewire for the real world speed.
     
  3. Dr.Pants macrumors 65816

    Dr.Pants

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    #3
    Yes, pretty sure you can - use FW to conect, as USB externals are too slow.

    You could also (this is more recommended then the above) use a 5.25->3.5 bracket on one of your optical drive bays, and keep the fifth drive internal. There are a few lone SATA ports on the MacPro, right?
     
  4. j2048b thread starter macrumors 6502a

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    #4
    I wondered about that as well?

    I have seen people put in a sata blu ray drive using one of the sata ports that are kind of hard to get to, so yeah there may be a couple, but i wonder how much i can add to the power supply?

    maybe there is a longer power cable where the drives would go?

    do you have a link for the bracket you mention?

    (or i could put the drive into where the other optical drive would go?)

    what about booting and using parallels and fusion off the same hard disk as mac os? is it possible to run them both off the same disc at the same time?
     
  5. j2048b thread starter macrumors 6502a

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    #5
    Thanks, i liked the others guys suggestion about using the other not so easy to get to sata plugs for the other disk drives!!
     
  6. gugucom macrumors 68020

    gugucom

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    #6
    Using the ODD SATA Ports (that is what they are called) is fine for OS X. You will perhaps have a problem if you are using them with Bootcamp. In a MacPro1,1 they will not be recognised by Windows as soon as you create a RAID. I'm assuming here it will be the same in the later MPs.

    What is happening there is that Windows installes legacy IDE drivers instead of AHCI drivers. But there are ways to solve this and set the four regular and the ODD SATA ports into AHCI mode. I can point you to the right thread if you need that.
     
  7. PhixionFilms macrumors 6502

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    #8
    ive heard this to be true by multiple sources.
     
  8. j2048b thread starter macrumors 6502a

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    #9
    Yhanks,

    I did get a link from one of the other posters, but i wonder if it would be an easier way to slipstream the drivers in ?

    not really sure how to do that?

    also my mac pro is a 3,1 not a 1,1 so would there be a difference with the sata ports not being set up in ahci mode ?

    thanks

    to all who has helped!!


    (also)

    if i set the other 4 bays into a raid mode, how exactly does that work? I know it will be a software raid, but is it 1 or 0 or?

    and if i do that and my 1st drive is my OS Leopard, then how will the raid be? Will it just back up everything from my mac to the raid array or? I am not to savy when it comes to raid!
     
  9. Tesselator macrumors 601

    Tesselator

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    Jan 9, 2008
    Location:
    Japan
    #10
    I can answer this part.

    Mac Pro absent a RAID Card solution, supports RAID levels 0, 1, and 10 (and 01). 10 and 01 are a sort of compound RAID level where you set up either the RAID0 and mirror it (RAID1) or in the case of 01 you set up the mirror RAID1 and stripe it RAID0.

    The procedure for setting up a RAID0 in Mac OS X for example, is to load Disk Utility.app, Click any volume or drive name, click the RAID button, set the name volume and type, drag the other members of the intended raid set and then click create. Depending on what you'll use it for mostly you may want to click the Options button and set the RAID block size too.

    This operation will wipe all data on all participating drives or volumes.

    I say drives or volumes because it is entirely possible to partition the drives first and then add those partitions (volumes) as your RAID participants. After you create a RAID you may not partition it. But partitioning a RAID or having multiple RAIDs on the same set of drives IMO isn't a good idea and will defeat at least some of the purpose of the RAID.

    I guess it would be fine to do something like set a 20GB partition on all drives and add those to the RAID and then leave the remainder of each of the drives in JBOD form (looking like single drives I mean).

    You want all participating drives or volumes to be the same size. If they aren't then your raid will be the size of the smallest multiplied by the number of drives for RAID0 and for RAID1 will be the size of the smallest.


    The advantages of RAID0 are that:
    • You get the total space (example: Four 1TB drives in a RAID0 = 4TB),
    • You get increased speed usually close to the drive multiple (2 drives = 2x speed, 3 drives = 3x speed, and etc.),
    • And you get a reduced access latency. Like seek speeds and rotational latency. This means that the drives can find and begin to load the requested files faster.
    The disadvantages of RAID0 are:
    • None that I can think of if you consider the entire stripe set (volume) as one single unit.
    • If however you visualize them in your mind as 3 separate units then the downside is that if one breaks then all the data from all 3 is lost - just like it would be on a single volume.


    The advantages of RAID1 are:
    • Increased speed. But not as much as in a RAID0. I guess it's like 1/2 for each drive added but I've not studied the particulars so I guess it could be less (or more?). Additionally to note is that only the speed of read operations will be increased. Writing will actually be slightly slower than JBOD (just a bunch of disks) or single disks.
    • Hardware level redundancy. This means that if one drive breaks suddenly you do not lose your data. It's not a 100% guarantee and sometimes the breakage may affect all drives or smear the data in such a way that it's also corrupted on the mirrors. It does not protect you from pilot error or software malfunction either and if data becomes corrupt on one unit it will likely be corrupt on the mirror as well. It's just a hardware level of protection via redundancy.

      Note: I don't know if seek access times are reduced or not but I would suspect not as the data is not interleaved as it is in a RAID0. In fact seeks may even be slower depending on the controller. <shrug>
    The disadvantages of RAID1 are:
    • You only get half of the total space. For example in a two 1TB drive RAID1 your volume size will only be 1TB. In a four 1TB drive RAID1 your volume size will be 2TB - not 4TB.
    • Only even numbers of drives or volumes may be used. 2, 4, 6, 8, etc. It's not possible to have a 3-drive RAID1. And only more than 2 drives may be used if the RAID 1 is a part of a RAID10 or RAID01 set. As far as I know it's not possible to have a RAID1 only four drive configuration. LOL unless maybe that's a RAID11 or something. <shrug>
    • Write operations are slightly slower compared to single volume or "JBOD".

    Looking up RAID in wiki will reveal a very nice overview of RAID and give you and explanation of all of the most common RAID levels. There's also a LOT of good information and discussion here at MR too. You can find most of it by searching or in the MR external search engine: http://mroogle.*************/

    EDIT:
    If you wish to install OS X on your RAID then you either need to go through the install process from the start as you would for any new drive or you need to use a utility like CarbonCopyCloner or SuperDuper to copy the installation from the original HDD to the newly created RAID volume. The later would of course imply that you did not use your current boot drive as one of the participating RAID members.


    .
     
  10. j2048b thread starter macrumors 6502a

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    #11

    WELL holy LORD that is pretty in depth and very very helpful!! thank you, i am still undecided about raid ing the mac pro, I have a yellow box comming that i bought off of ebay and it will allow me to use up to 4 drives and i will do that when ever i get it,

    what is the purpose of even setting up raid in the mac?

    it may defeat the purpose for me to raid my mac, as i do not do video or music editing of any sort and want to keep all my music/videos and pics somehow so they do not get lost and o corrupted. (hence the raid for me)

    I have been reading a lot about unRaid and may go that route!!


    (i hope to)
    buy an older used G5 case or a mac pro case and alter it a bit to set everything up in that, then just add my drive array and parity drive, (as that is how it look as though you do it),

    it just seems that you may need a pc to use in order to set up all of the unRaid?

    Thanks so much for all the help
     
  11. Tesselator macrumors 601

    Tesselator

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    #12
    Speed mostly, as stated above.

    Sounds more like you want a backup solution. No RAID by itself fits that description. UniqueRAID or UnRAID is just a way to permit you to view your storage as if it were one large file system, even though each data disk has it’s own file system. It's security level is a bit like RAID5 from what I gather but with zero speed benefits. Also I didn't think that worked with OS X. Does it?



    Sounds like an unstable PITA to me. <shrug> NAS and external RAID5 separately or combined might work for ya. <shrug> <shrug>
     
  12. geoffreak macrumors 68020

    geoffreak

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    Feb 8, 2008
    #13
    Something that Tesselator forgot to mention is that RAID 1's speed gains are only in reading. Writing will actually be slightly slower than JBOD (just a bunch of disks) due to the fact that the data has to be written twice. The difference is minimal, but it can be noticeable when using applications requiring heavy writing to disk.
     
  13. Tesselator macrumors 601

    Tesselator

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  14. j2048b thread starter macrumors 6502a

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    #15
    Thanks everyone for the help and eduMACation i have received about RAID!!!

    cant wait to dive in and see what happens!!1

    Tsselator, i am a grasshopper you are the master!!

    thanks for the insight!!
     
  15. gugucom macrumors 68020

    gugucom

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    Munich, Germany
    #16
    I believe that a MP3,1 will be the same as MP1,1 with regard to AHCI drivers, but I'm unable to confirm at this time.

    Slipstreaming would be done with vLite, but it will not save you the hassle to do the Johnsock mod and the registry mod. If you do not do these things you get a BSOD every time you start and your installation is a goner. That's why backup is essential before you mod anything.
     

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