User on external RAID - not supported, say Apple

Discussion in 'Mac Pro' started by slater-k, Jan 6, 2015.

  1. slater-k macrumors regular

    Jan 13, 2008
    Hi Everyone,

    [I wasn't sure of the location to put this thread, but as nearly everyone who has a user on an external RAID will be using a MacPro, i thought this the best place.]

    So the Q: My user is on an external RAID box (Areca 8050) which is great, and meets my needs. However, i had one of the discs fail, and once i'd replaced it, the OS wouldn't recognise my user, and that ended up causing me a lot of grief.

    When i contacted Apple for support, they told me that OS X doesn't support having a user on an external RAID. An external disc - yes; but external RAID - no.

    Is this the experience of others?
    Is there an easy way to transfer a user back onto the main HD, minus all the data that i'd like to keep on the RAID?

    Many thanks in advance :)
  2. AidenShaw, Jan 6, 2015
    Last edited: Jan 6, 2015

    AidenShaw macrumors P6


    Feb 8, 2003
    The Peninsula
    Did you contact the Moron Bar instead of the Genius Bar? That sounds like bad advice.

    The system should seen an external hardware RAID as a simple external disk. (If it's T-Bolt, it could even appear as an internal disk.)

    There might be issues with software RAID on external disks (Windows refuses to create software RAID on removeable disks), but hardware RAID emulates a simple disk to the host.
  3. burnsranch macrumors member

    Jun 19, 2013
    That is interesting. I have a nMP and have my main user on a Gtech raid. I have just ordered a 20tb thunder bay raid 5. It is a software raid and I wonder if are issues if you run the software from an user on the raid drive, verses running from a user on the internal SSD drive.
  4. xav8tor macrumors 6502a

    Mar 30, 2011
    I'm not sure about moving the User folder over to a RAID, of which I have two: A G-RAID via TB and an OWC 4 bay via USB 3. The G-Raid via TB is NOT useable as a boot drive, that much I know after speaking with them yesterday trying to make a mirrored partition evenly split between OS X and Win 8. You can't do that because it is a software RAID controlled by the OS. Even though they said there was no way, I did manage a FAT32 partition that works both ways, but I cannot live with the 4 GB file size limit. Software RAID almost always has quirks. The fact that the TB drive in RAID isn't bootable is just nuts given how hard Apple pushes its alleged fantastic attributes. I was told, however, that it might work if you configure the G-RAID as JBOD, which kind of defeats the purpose.

    On the other hand, the USB 3 OWC RAID four bay box is hardware controlled and you can choose JBOD, 0, 1, or 5, the latter being the best of both worlds. It's only about 40 MB/s slower than the G-RAID when striped, so less than 20% slower, more capable, and a lot cheaper than the G-RAID. OWC support/service is also great. The first one had a bad temp sensor so the fan ran flat out all the time. They shipped me a new one first, no questions asked, and all I had to do was foot the bill for shipping the old one back, which via UPS ground, would have been about 15 bucks.
  5. hfg macrumors 68040


    Dec 1, 2006
    Cedar Rapids, IA. USA
    If your G-Raid requires a driver for OS X, then it will not be bootable because it needs the driver to be loaded to access the drives. The driver isn't available until after the boot process.

    If it is accessible as JBOD without any special drivers, you can create the RAID 0/1 configuration with Disk Utility and then it will be bootable.
  6. goMac macrumors 603

    Apr 15, 2004
    I don't think technically AppleCare suggests you keep your data on any external disk (besides stuff like the Mobile Caching/OS X Server/Active Directory) stuff.

    This kind of needs more context. Are the files there if you browse the drive normally? Are they all permissioned correctly? Did the location of the disk change to the system?
  7. xav8tor macrumors 6502a

    Mar 30, 2011
    I tried...numerous times. Didn't work, so I called them. G-Tech said it doesn't work, and it is in fact so stated on their support page:

    Can I boot my Mac from a Thunderbolt drive?

    The G-RAID Thunderbolt is not supported as a boot volume.
  8. slater-k thread starter macrumors regular

    Jan 13, 2008
    I had first rebuilt the RAID, and all the files were there, and permissions correctly set.

    The problem was that the OS (in system preffs) wasn't able to set the home directory back to the top level folder on the RAID volume. I could navigate to it, and select it, but then the OS would make a new folder and append a "1" to it, so my Home Directory would become "MyUser 1" instead of "MyUser" and point to the new and empty folder "MyUser 1" ... hence the problems for me.

    My RAID is a T-bolt external, hardware RAID, and so yes, my expectations were similar to yours. However, it turns out that once i'd rebuilt the RAID, and everything was back to normal on it, the OS had many difficulties being pointed back to it as my Home Directory, and the only solution that i could make was to rename the folder, and then repeatedly try to point the OS to it ... but even with the new name, it took many attempts before it stuck.

    Apple 2nd level support said that having your user on an external disc is supported, but is not supported with an external RAID ... go figure!

    So my dilemma now is whether to switch my user back to the nMP's hard drive (256Gb and so rather small) incase another disc on the RAID fails, and if so, how to do that while keeping all my permissions and settings as they currently are?!
  9. burnsranch macrumors member

    Jun 19, 2013
    I have noticed that the OS has problems when you accidentally disconnect the user home raid from the system I think I had to redefine the user directory in system preferences, and then reboot a couple of times to reconnect it. I have another raid drive coming I will be moving my home directory to and will experiment a little more.

    I am going to be using soft raid, where my existing raid drives are hardware raid.

    Apple did not do their work, when they designed a modular system. Moving the user directories to external drives needs to be flawless. I cannot even run compressor on my 256gb internal drive as the cache for compressor is in the user libraries. I sure have not found any design guidelines for their modular platform nMP.

    I thought I left these types of issues behind when I move from a dos platform to a mac.
  10. goMac macrumors 603

    Apr 15, 2004
    I'm not entirely sure that going through System Prefs will allow you to use an existing folder. I think it will only do a brand new folder, hence it's behavior.

    Try one of these:
  11. Bwa macrumors 6502

    Jun 20, 2007
    Boston & San Jose
    I have my home directory on an Areca 8050T2 on my Mac Pro, it works fine. But if the Thunderbolt cable goes away, of course there are issues.

    I've been running my home directory on an external Areca RAID since 2009 (was a SAS chassis with a 2008 and later a 2012 Pro).
  12. slater-k thread starter macrumors regular

    Jan 13, 2008
    Yeah, mine was particularly troublesome - glad to know that once you got it sorted, it stuck - as i was worrying about whether there would be more problems down the road. Do let us know how it goes.

    That's a bit toooo complicated for me! As the poster says "be careful! A wrong edit in the user Open Directory database might make your system unusable", and so i'm a bit shy of that! Good to know though, so thanks.

    Apple suggested having the user on the main HD, and then just the large things (ie pics, movies, projects etc) on the RAID. Are you happy enough with your set up to not go with their suggestion?

    Personally, i really like having all of my user on an external RAID for ease of back up, but i do worry about the time and grief it took to get things back to normal after the drive failure. Admittedly, drives don't fail that often, but if i was chasing a deadline, it could get messy. For that reason, i'm still undecided as to whether to keep it or migrate it.

    (Like you, i've had my user on an external RAID for years, and never had problems like i had in this case, before.)
  13. burnsranch macrumors member

    Jun 19, 2013
    I have had a nMP base mode for about three weeks. It comes with 256 g of SSD, which implies I have to store my data on external drives.

    Compressor uses a Cache in the user/library, so if I want to use that program, I need to move my user directory to an external disk. If I use the side panel to manage my data then I also have to move the user to an external disk, unless I want to dig up some 30 year old unix skills and map the directories to an external drive.

    I just imported 8TB of videos into FCPX. So I manage a lot of data. I just bought a 20 TB read5 thunder bay raid five drive and partitioned with a 2TB home drive and a 13 TB videos storage drive.

    The first issues, is there is no easy way to move a user directory from one drive to another. There are unix commands to accomplish this, I could not get it to work by just copying the user folder to the new drive and relinking it through the user system preferences panel. I just had to rebuild the user and copy my user data over.

    Time machine does not work very well with Video libraries. I prefer to back up my users data with time machine, and my video data bases independently. By partitioning a 2gb home drive I can use time machine and airport to back up my system and user files and an independent program to back up my video files.

    I built my raid drive with soft raid installed by a root users on the SSD drive. This way I could insure the files to control the raid were not store on the raid user. When testing the raid by unplugging drives hot and rebuilding the raid, I had no problems with the user on the raid drive.

    While I bought my nMP as an impulse buy, It was clear by the marking this unit is designed to support external storage via thunderbolt connections. This is a different design philosophy than the tower designs. I ponied up for the a professional grade computer and I expect professional grade tools and support with it.

    If the product does not support external users, they have misrepresented the product. As a professional, I might want a different login account and storage system for each of my customers. I might have to take my user and plug him into different mac systems. There are a lot of valid reasons to support users on external drive.

    I have not found anything close to a professional white paper on system design guidelines from apple for the nMP and to be honest, I am a little concerned about their long term support for the professional world.

    I also can see that using raid technology with SSD is nuts. If there is a new SSD/thunderbolt technology that will replace raid drives, I can accept the short term issues and work around them. As a professional, I need to understand what their long term plans and directions are to keep my system design correct.

    I would assume if I have to rebuild my raid from a complete failure, should be able to recover it from time machine. I have not tested it, but this is the stuff that should be sold in a professional level machine. This was one of the reasons i move to apple couple of years ago, and why I bought the nMP.

    I also use Parallels Desktop for my dos programs I have the system image on the raid drive. That seems to work fine also.

    I don't see any logic in having the system files on an external drive with the nMP. It made sense in a hard drive (DOS) world but in an SSD environment it makes far more sense to keep the system files local and the user/data on external storage. Raid makes no sense at all in an SSD world. but it is clear we on on the front edge of that movement.

    The big advantage for me is to be able to reinstall the system files independent from the user data. I only tried it once and it was not as clean as I would like, I think I had to rebuild the user instead of relinking it, but that was not a huge deal compared to trying to recover from with my mess of data on a system drive.

    I am impressed with the design of the machine, it has a lot of potential, external GPUs, External thunderbolt storage controllers, we will just have to see where it ends up.
  14. antonis macrumors 68020


    Jun 10, 2011
    You did put a lot of points on the table. However, in a context of a *nix system, the following rule of thumb should be taken under consideration: user home, user data, and system files should be handled separately (all 3 of them).

    To clarify the above, a valid setup would/should be:

    1. The users home folders in the internal storage. Considering the above, no other data should exist in there, except the user's application preferences. So, no much space should be required for this.

    2. The user data on an external storage. That's the main content, hence that's where the space will be occupied. Applications should be configured to use the external storage. If needed, you could also protect the users' data from each other. After all, it's a unix, so it is built over the user isolation concept out of the box.

    3. System files (OS files) should also be on the internal storage.

    In other words, let the OS-related files/directories (system files and user home directories) on a unified always-available trusted storage (internal) and just handle the data externally, as you like. After all, these are the data that will take all the real space.

    Concerning the backup/recovery, I'd just use Time Machine for the system files (operating system and user homes), but if the system serves more than one user, I'd only use TM to restore OS files. Then, the user accounts could be restored individually, using the Migration Assistant as needed (using the TM backup of course). I'd use a different externalized strategy for the backup of the user data (the ones on the external storage) and would not bother the operating system with this effort.

    I think the above scenario is the most "clean" setup for this. Another variation of the above, could be using symbolic links for the users homes to the external storage. But, just in case, even then I'd keep the administrative account's home in the internal storage.

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