RAID Setup Advice - External iTunes Media Folder

Discussion in 'Apple TV and Home Theater' started by ryedarrow, Dec 14, 2013.

  1. ryedarrow, Dec 14, 2013
    Last edited: Dec 14, 2013

    ryedarrow macrumors member

    Jun 30, 2012
    Current Setup:

    I set them up in RAID 0 and have about 5.5TB of usable space. Problem is I have 225GB free.

    What I am looking for:
    1. A larger 4-bay array, anything out there better than this Mediasonic 4-Bay?

    2. After some research, I think it would be smart to move away from RAID 0 to RAID 5. Any thoughts against doing that?

    3. Since I already have two 3TB Barracuda Drives, all i would need to do is buy two more of the Seagate Barracuda 3TB to complete the 4-Bay setup.
    How do I get the data off my 6TB RAID 0 into the new drives? From what I understand I can't start a new RAID 5 configuration without 3 drives and I will only have two new drives. Any advice?

    4. If I were to get this 8-Bay enclosure instead of the 4-Bay, I could buy 3 new drives, set them up in RAID 5, then copy the data over.

    Could I then wipe my two current drives and add them to the new setup? Giving me 5 drives total? Can you add fresh drives to a RAID 5 array?

    Thanks everyone for your help
  2. mac8867 macrumors 6502

    Apr 5, 2010
    Saint Augustine, FL
    So, if I understand you correctly, you currently have 2 3TB drives configured as JBOD (Just a bunch of disks) with striping (RAID 0). To reuse those drives into a new parity raid set (raid 3,4,5), you would first need to backup the data - as you say. The question is, how much space are you using in your current 6TB configuration? That is the amount of space you would need to create your backup.

    Depending on the device you pick, you would configure a 3 drive raid set, copy your data to the array. Once that is done, you should be able to expand the raid set by introducing a fourth drive and adding it. You may also be able to add a fifth/sixth... drive and specify it as a hot spare. In that configuration, if one drive failed, the spare would synch into the array and maintain your protection. (I should point out, this will only work with raid 5, not 3 or 4 as they require synchronized spindles)
  3. westrock2000 macrumors 6502a

    Oct 18, 2013
    Yes, it is a very good idea. It gives you protection against the most likely thing that will happen to your data, which is a failed hard drive. It won't protect you from a many number of other circumstances, but it will from a drive going bad (which is why people stress it's not "backup".

    You are correct, there is nothing you can do to integrate your current setup with another setup, that doesn't end up with a hodge podge mess.

    Here's my big secret on how to get around it. Go to a brick and mortar store and buy two 3TB or 4TB drives. Copy all the data to them. Create your RAID setup (including using your original 3TB drives). Copy all the data back over. Then return the two drives you bought claiming your old computer only sees 2.2TB on each (and be sure to wipe them before returning). I know it's a bit unethical, so go to somewhere like Fry's and try to find ones that are already opened so you don't make them take the mark down hit on a perfectly good item.

    The only downside to you is floating the $300-$400 while you have the drives. Also make SURE the store you buy them from does not have a restocking fee on hard drives. I had no problem with Fry's. I think Microcenter has the same policy, but double check. I even asked the guy at the store "Hey, um, if my computer only sees....", and he cut me off "Ya , if it doesn't see the whole thing you can return it".

    As far as adding drives to a RAID setup, that depends on the specific software or hardware you are using. It also depends on HOW the expansion occurs.

    First make sure that you can expand, not all RAID systems allow this. Now consider the two ways expansion can occur.

    1. A new drive is added to the original array. In this example you create a RAID5 array that is 3x3TB. 2 data, 1 parity. When you add another drive it now becomes 4x3TB. Still RAID5, 3 data, 1 parity. This is how most traditional hardware RAID units function. The upside is you easily maintain your single array. The downside is that your original choice of parity can become a weak spot after only a couple drives are added. 5 drives is really the max for RAID5. And even then you need understand, you are taking a risk. Each time a disk is added, the array has to be rebuilt to spread the data across the members.

    2. The other way is how ZFS implements it. The concept is that whole array is called a pool, and within that pool is arrays that all add to the pool. So you start with 3x3TB in RAID5. You cannot ever change this array once it is made. On a side note, you CAN replace them each with 4TB drives and grow that way though. However you can add another 3x3TB RAID5 to that pool and you will now have two 3x3TB arrays consisting of 4 Data and 2 Parity. And you can do this over and over again, all while maintaining 1 collective pool. When a new array is added to the pool, ZFS just starts writing to the new array, so there is no rebuild. Only when replacing existing drives with larger drives.

    Personally I am a big fan of ZFS, and it's the reason I switched back to Mac because it doesn't exist in Windows. ZFS also has another feature that makes it amazing because it creates checksums for all data on the pool. So not only is the data protected from a hard drive physically failing, but it's also protected from bits being written incorrectly.

    That being said ZFS is currently having some stability issues on Mavericks. So you would need to do some trial runs first. Which is a good idea to begin with, to get comfortable with how ZFS works.

    Also, ZFS has some "magic numbers" when it comes to how many drives should be a RAID5 array. The most common are 3 and 5. When you make vdev's (arrays) of this size you have very low overhead. When I had my 5x2TB on Windows I had 7.28TB available (1.82 x 4). When I switched to ZFS with the same drives I got 7.86TB.
  4. ryedarrow thread starter macrumors member

    Jun 30, 2012
    THANK YOU! Very helpful. I like your idea to check out some opened HD's for quick storage.

    I've always used Disk Utility to format the drives in OSX Extended. How do I do ZFS, is it hard to implement?
  5. paulrbeers macrumors 68040

    Dec 17, 2009

    I'm not going to get into advantages of ZFS vs HFS+.

    What I am going to warn against is RAID 5. I used to be a huge fan of RAID 5 and actually had two RAID 5 controllers in my file server. However, when one of the controllers died and I was unable to get replacement, I had be really creative with getting the data back. After that, I decided I would only use Software RAID options from the OS so that no matter what happens with the computer, I just need to throw the hard drives into another computer running the same OS. Now I just use RAID 1 (mirrored) controlled from OSX. With 3TB hard drives going for $85 on sale and I've seen 4TB as low as $120, only getting half of your storage (compared to n-1 for RAID 5) is not nearly as big of a financial hit as it used to be.

    I simply buy the cheap Mediasonic 4 bay USB 3.0 enclosures. So far I have bought 3 with one dud (Amazon took it back no questions asked) and I have my 4th one sitting in the basement waiting to have 4 more 3TB drives added to it (just need to find time).
  6. ryedarrow thread starter macrumors member

    Jun 30, 2012
    So You buy the Mediasonic 4 Bay ProBox instead of the ProRaid 4bay?

    Then you format to ZFS and RAID 1? With ZFS you can keep adding to the "pool" as mentioned above?


    I see from the WIKI:
    Mirroring, the other ZFS RAID option, is essentially the same as RAID 1. The difference is that ZFS allows any number of discs in the mirror, for instance, you could create a mirror consisting of three disks, or even eleven disks.[77]

    So You just keep adding 4-Bay enclosures and it mirrors and mirrors and mirrors?? This is incredible!! Thank you for sharing.

    Do you use:
    1. maczfs
    2. OpenZFS
  7. westrock2000 macrumors 6502a

    Oct 18, 2013
    I Have had similar experience with hardware RAID, and being tied to that exact hardware or that family of hardware is drawback to hardware RAID.

    However ZFS is a fully self contained file system and is meant to be portable. You can take a ZFS pool from ANY operating system and open it on ANY other operating system that can support ZFS (limited to Linux and Unix currently). The only stipulation is that you need to be using a version of ZFS that is at least as new as the version that originally created the pool. Since the OSX versions are relatively older versions, you should have no problem if you ever wanted to move the pool to a Unix or Linux based system.

    That also means that you can move the pool to another Mac if you ever wanted to.

    The two choices are MacZFS and ZEVO. I had to use MacZFS because ZEVO will only work on a 64 bit kernel, which my older Mac Pro does not have. You will have to check into the status of ZEVO on Mavericks, as I haven't followed them since I can't use it.

    ZFS isn't hard to implement. You have to use the Terminal to do everything. But there are just a couple lines to type in when you are setting up the arrays and then after that you really don't need to do much. I'm not afraid of a Terminal though, in fact one of OSX's strongest aspects in my opinion, is having access to the Unix under pinning's.
  8. linds15 macrumors 6502a

    Oct 16, 2012
    Great White North
    how do you like the mediasonic? been debating one since i just want a basic DAS for media storage, nothing fancy
  9. paulrbeers macrumors 68040

    Dec 17, 2009
    Overall I am happy. The first one I received was rock solid. The second one kept disconnecting, but the third seems as solid as the first. Considering it is the cheapest USB 3.0 option, I am very happy. I haven't run any disk speed checks on them, but they seem to be fine. My only complaint was the second one was a dud, but Amazon took it back with no issues.

    One item I haven't been as pleased with is that if you leave the fan on "auto" it seems just to run the fan at the slowest speed and my drives have gotten quite warm. However, if you hit the fan button then you can choose one of three speeds for the fan. I find the second fan setting to be a good cross between cooling and noise (the fastest fan speed is fairly loud!). I've thought about replacing the fans, but ultimately they sit in my office and the only person who would hear them is me.

    I should have my third (technically fourth if you count the unit I returned) up and running this weekend.
  10. ryedarrow thread starter macrumors member

    Jun 30, 2012
    Are you on Mavericks and which ZFS system do you use?
  11. ryedarrow thread starter macrumors member

    Jun 30, 2012
    Hey Paul! I'm going to pull the trigger and try to duplicate your setup. From a little research looks like MacZFS is the only solution using Mavericks. Is that what you use?

    The cheapest 4TB drive i could find is $159 on amazon, where do you buy yours?

    My plan is to buy (4) 4TB drives, the Mediasonic 4-bay, format them all into a ZFS pool, then use OSX software raid to implement RAID 1.

    Am I missing anything?
  12. paulrbeers macrumors 68040

    Dec 17, 2009
    Truthfully I don't use ZFS at all. That's why in my original post I stated I wouldn't get into ZFS vs HFS+. I keep it simple.

    As for drives, I actually use 3TB drives only because the per TB cost is considerably lower and I usually buy them on Black Friday. I always buy external drives and just rip the hard drives out of them because it is usually considerably cheaper to do that (when they are on sale). For example, on BF I bought 3TB external Toshiba's for only $85 and if I buy them as internal bare drives they are $120.

    Just some food for thought. 4TB will be expensive no matter what route you go since they are the highest storage option on the market currently, so like anything you always pay exponentially more for the fastest/largest/etc.
  13. linds15 macrumors 6502a

    Oct 16, 2012
    Great White North
    bumping an old thread since its on track with where I'm looking to go. paul, you said you don't you use ZFS of HFS, do you just throw the drives into your media sonic and go with the mac raid setup. I'm looking at the media sonic 4 bay, and am looking for an easy way to handle all my media. i was debating between jbod or raid 0, as i want to maximize storage as the essentials are all backed up elsewhere.

  14. paulrbeers macrumors 68040

    Dec 17, 2009
    If you are just doing Media, I would NEVER consider RAID 0. One drive goes, all media is lost. You don't need the additional bandwidth that RAID 0 gives for serving media. Might as well just go JBOD. Just my opinion though.
  15. grahamperrin macrumors 601


    Jun 8, 2007
    A suitably configured ZFS pool should suffice. No need to think about complementing ZFS with AppleRAID.

    Be aware that both MacZFS and OpenZFS on OS X have problems with Spotlight:

    Also: iTunes on ZFS RAIDS disk, SLOW load


    How many disks should you put into a RAID-Z stripe? Data reveals fallacy of premature optimization:

    ZFS RAIDZ stripe width, or: How I Learned to Stop Worrying and Love RAIDZ » Matt Ahrens

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