Can software RAID volumes be expanded?

Discussion in 'Mac Pro' started by funkahdafi, Mar 24, 2009.

  1. funkahdafi macrumors 6502

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    Mar 16, 2009
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    Planet Earth, Old World
    #1
    Hi,

    I popped a new drive into my mac pro that's running a 2 disk raid-0 stripe set. I thought I could add the new drive into the existing raid array but I fail. Disk Util won't let me drag the new drive into the raid set.

    Isn't this supposed to work?

    Thanks
     
  2. nanofrog macrumors G4

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    May 6, 2008
    #2
    I don't think so. :(
     
  3. PowerPaw macrumors member

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    Jan 15, 2009
    #3
    Its striped not concatinated so no, its not an option to add another disk.
     
  4. belvdr macrumors 601

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    Aug 15, 2005
    #4
    Looks like another reason hardware controllers excel over the software counterpart.
     
  5. nanofrog macrumors G4

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    May 6, 2008
    #5
    Yup. :D :p
     
  6. funkahdafi thread starter macrumors 6502

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    #6
    How hard is it to implement something like a Rocket Raid card? I guess the cabling from the drive bays to the card can be tricky?

    Which Rocket Raid would you suggest? It should be able tro drive internal as well as external eSata drives. And it should be able to boot OS X.
     
  7. nanofrog macrumors G4

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    May 6, 2008
    #7
    Details would be needed before anyone could really help.

    Which Mac Pro?
    How many drives now, and planned in the near future?
    Which type of array? (0/1/10/5/6/50/60)?
    OS X only, or multiple OS's?
    Will you boot from it?

    It can be done, even in the new '09 models, but these are a little more difficult, as the HDD ports were soldered to the logic board this time. It's easier and can be less expensive on the '06 - '08 models (internal configurations).
     
  8. funkahdafi thread starter macrumors 6502

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    #8
    I am upgrading to the 2009 model (from a 2006 model). Right now I have two 1 TB disks in a raid 0 array and the current plan is to upgrade this to a three disk stripe set and a separate non-raid disk for time machine.

    However, I am still figuring out the setup. I read about MaxConnect extension bays to get 6-8 disks into the machine so I was thinking of doing RAID 10 over 6 disks or maybe RAID 5. Not sure about that yet though as I dislike external disks and need to fit my time machine disk somewhere. So planning is still open.

    What's the difference between the soldered HDD ports on the logic board vs. the previous models?

    How would you run cables to a RAID card anyways? I assumed the hard drives would be connected directly to the raid card... no?

    Thanks! :)
     
  9. cmaier macrumors G3

    Joined:
    Jul 25, 2007
    Location:
    California
    #9
    Just curious - with Apple's hardware RAID card, can the volumes be expanded? (e.g.: assuming RAID 5, can you pull out a drive, replace it with a bigger one, rebuild, repeat the process for each drive, and then use the extra space?)
     
  10. nanofrog macrumors G4

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    May 6, 2008
    #10
    If it's set up in software RAID, you'll lose the data on them switching to a hardware solution, so make a backup of it first. ;)
    If you plan to stay internal on the '09 MP, you have some limitations, or even "brick wall", depending on specifics.

    1. Software RAID of the 4 HDD bays. You may be able to add another 2, but would have to relocate the optical drive(s) to external enclosures. No ability to run RAID 5 or 6. OS X only, so no other OS's.

    2. Apple's RAID card can run the 4 HDD bays only, but is hardware. It provides support for RAID 5 & 6. No ability to run other OS's.

    3. 3rd party hardware, INTERNAL. Remove the optical drive(s) to external enclosures, and use the optical bays for HDD's. Using 3.5" drives, you're likely to be limited to 4 HDD's. To go over that, you'd need to go with 2.5" drives. You can obtain cards that can boot, and operate multiple OS's.

    Beyond this, is 3rd party EXTERNAL. It gives you the greatest options, but the enclosures drives up the cost. You can acquire cards that boot, as well as support other OS's. Drives are limited to the port capacity of the card/enclosure combination used.

    On the new '09 model, the drive data is passed via traces on the board itself to slot 4. It will only work with Apple's RAID card however, as the SATA controller must be switched off on the 4 HDD bays in order to give control to the card. Not possible with 3rd party ATM, and I doubt this will change due to Apple's EFI (where the switch function would be located). If a 3rd party figures it out, there's a good chance they'd end up in a legal battle over Intellectual Property.

    On the '06-'08 models, there's a cable that runs from the logic board to the back of each HDD bay. It carries both data and power.

    Using these, you unplug the data side from the logic board, and plug it into the RAID card's MiniSAS port.

    Apple eliminated this in the '09 models, hence the added difficulty of using 3rd party RAID gear. External is the easiest, but isn't the least expensive way to go, depending on needs. If you wanted something like an 8 drive primary and another 8 drive secondary (backups), external would be the only possibility. A single, small array, could be done, if you're willing to relocate the optical drive(s) to external enclosures.

    The only other think I can think of, is if a company such as MaxUpgrades or Trans International come up with a sled that can use a MiniSAS Fan Out cable or a variant that includes power (SFF-8470 ends for the drives). It would have to be shorter as to not reach the SATA connectors on the logic board, and still have enough room to plug in the data and power connections. I'm not sure there's enough room to do this, so no idea if it's truly possible, let alone if it would actually happen. :(
     
  11. nanofrog macrumors G4

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    #11
    Yes. :) Just like any other true hardware RAID card (not Fake RAID). ;)
     
  12. cmaier macrumors G3

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    Jul 25, 2007
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    California
    #12
    Cool, thanks. I have two infrant NAS's, each of which I've ended up growing at least once (very easily), so I'm always suspicious of being locked into a situation where the only way to grow is to copy the entire volume and then copy it back.

    I'm trying to decide what I want to do for storage when I buy a '09 MP. Leaning toward apple hardware RAID, with time machine back up onto one of the infrants, though I briefly considered 0+1 software RAID with a 3rd party card and enclosure for main storage.
     
  13. nanofrog macrumors G4

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    May 6, 2008
    #13
    You'd want to reconsider the 3rd party alternatives if you would need to exceed a 4 drive array though. This is too limiting a factor for some. But won't be a problem if you know you'll be able to keep up with any growth with 4 drives, only changing out drives for ones with larger capacities. It may open you up to the "write hole" issue (RAID 5 & 6) though, as the UBE's aren't increasing to mitigate the issue. :(

    No easy answers for this yet, as ZFS/RAID-Z/RAID-Z2 isn't yet available across all major OS's either. :(
     
  14. funkahdafi thread starter macrumors 6502

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    Planet Earth, Old World
    #14
    @nanofrog: Thanks for your detailed response. I really appreciate that.

    So you are saying that internal hardware raid in the 09 models is completely impossible right now unless I use the Apple card or "hack" the optical bays?

    Since I am still thinking of only doing raid 10, I might as well just skip hardware raid and keep using software raid. I would need to use an external eSATA enclosure to get my six drives. I am wondering if eSATA can give me the same performance as internal SATA?

    Just thinking... if an external enclosure with two disks only has one eSATA port, wouldn't that limit the performance?

    My current idea is to populate the internal 4 bays with 4 * 1 TB and use eSATA with 2 * 1 TB. This way I could have two raid 0 stripe sets (2 * 3 disks) and mirror them with raid 1. However, if the eSATA does not perform like internal SATA, that will be a no go.

    Any thoughts?
     
  15. funkahdafi thread starter macrumors 6502

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    #15
    That's interesting. How exacty do you use time machine on a NAS? I was under the assumption that this was impossible. My network volumes don't show up in the time machine prefs...
     
  16. ildondeigiocchi macrumors 6502a

    ildondeigiocchi

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    Dec 30, 2007
    Location:
    Montreal
    #16
    Are there any RAID cards in the 100-250$ range that offer RAID 0, capability to boot 0SX, and use bootcamp for Windows XP and 7?
     
  17. nanofrog macrumors G4

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    May 6, 2008
    #17
    No problem. :)

    Details are really needed when dealing with RAID. Otherwise, you're libel to end up with a system that won't suit your needs, or possibly not function at all.

    Not quite. ;) You can, but it would mean removing the optical drive(s) and placing them in external 5.25" enclosures, and using the bays for the RAID drives. Depending on what you can buy or make, you can squeeze in 4x 3.5" HDD's, or even 8x 2.5" drives. Perhaps a little shoe-horned, but it's possible. Somehow I think many might not want to place the optical drives externally though, as it's not that attractive.

    eSATA runs at the same speed as SATA (300MB/s). :) Just the cables are slightly different (shielding is added).

    Why would you need to use eSATA? (Necessity)?

    eSATA can simplify things, and has a lower cost associated with it, but it isn't the fastest way to go. Most of the time, multiple drive enclosures use a Port Multiplier (PM) to switch all drives on a single SATA port, hence the throughput limits. It may, or may not matter, depending on your throughput requirements. For small arrays, it won't really make a difference. Ideally, you want 1 port attached to 1 drive. An eSATA card and 2 simple enclosures w/ eSATA ports wouldn't be too terrible, but it might hit the cost of a better RAID card, depending on what features you want. You'd have to run the numbers.

    In this case, PM enclosure, there would be a penalty in throughput, but for two drives, it may not be bad. What I'm not sure of, is if it would make a difference in operation (set-up even possible) under OS X.

    To explain, you'd have individual drives attached internally, but I don't know how it would "like" these being added with another two via a PM device on a single port. The drivers may not be capable of it in an OS X environment. :confused:

    See above. ;)

    It's the OS X aspect I'm a little uncertain of, as I've not used PM enclosures in a good while, and not split in the manner you want. Never on a Mac, as it happens. :confused:

    I stick to RAID cards, and software based ZFS/RAID-Z/RAID-Z2 via iSCSI/AoE rigs, when needed, for external backup (DIY). Otherwise, I just make a duplicate array (not a mirror).

    Maybe, but it would take some searching, for sure to hit that price point. All you'd really be able to find is "Fake RAID", which is nothing more than a drive controller chip, firmware (for boot), and drivers. NO cache, IOP, etc.

    You might want to check out HighPoint, as they're going to be your best bet. SATA/eSATA cards from other vendors as well.
     
  18. funkahdafi thread starter macrumors 6502

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    Planet Earth, Old World
    #18
    Guys, my Mac Pro just arrived. Will you please excuse me while I am gone jumping around in the house? :)

    Seriously. I am out of here until I got my new baby set up.

    Will do it the easy way for now: 3 * 1 TB in Raid-0, 1 * 1 TB single disk for time machine (heck, I might even spare a 100 gig partition to play with that other thing they call OS... what's that name again... :D ).

    Happy. Out.

    Thanks!
     
  19. nanofrog macrumors G4

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    May 6, 2008
    #19
    Keep in mind, once you decide to make changes, the data will be gone, so back it up. Then sit and wait, as the initialization process may take awhile. ;)

    Now go have fun with your new baby! :D
     

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