Looking for a good RAID 1 (Mirrored) Enclosure...

Discussion in 'Buying Tips and Advice' started by OCDMacGeek, Nov 12, 2007.

  1. OCDMacGeek macrumors 6502a

    OCDMacGeek

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    Jul 19, 2007
    #1
    I know there are tons of threads on external hard drives. However, these threads rarely discuss (and not fully) the best RAID 1 enclosures. I am no expert on the topic, but I believe that a RAID 1 mirrored enclosure is perfect for my needs.

    I have all of my media on an external disk, but I need to ensure that it this disk goes bad I won't lose everything. As far as I understand it, if one disk of a RAID 1 mirrored setup goes bad, you are still good to go as long as the other disk is fine.

    What are your recommendations for good RAID 1 enclosures? I would like to get a 1 TB setup, cost permitting. If it costs too much, I would go down to 750 GB.

    Is it possible to buy two external drives and combine them into a RAID 1 setup through software?

    Thanks for your help.
     
  2. giom macrumors newbie

    Joined:
    Nov 15, 2007
    #2
    Hi,

    I've been looking to buy a raid 1 setup too... and so I'm interested in what others might say about this topic.

    Right now the most interesting Raid1 setup I found is
    http://eshop.macsales.com/item/Newer Technology/GM8U2KIT0GB/?source=webnov13
    It costs $929.99 dollars for a 1TB raid 1 mirror setup or 600 dollars for 750Gb (a much better price)
    There is a review on this webpage
    http://www.macobserver.com/review/2007/07/20.1.shtml

    Now the problem for me is that while it looks good it has no esata connector.... And I was planning on modding my mac mini to use a sata-to-esata cable on the sata connection to the internal harddrive so as to use this external harddisk as the boot hard disk of my mini (to get a great file server)....

    Does anybody know such an enclosure with both firewire and esata connectors reasonable price (less than 200 dollars w/o harddisk) and hardware raid1 ?

    As for answering your question about software raid, it seems possible but from what I read there will be a bit of hit on performances (because the cpu will be doing the job)
     
  3. JesterJJZ macrumors 68020

    JesterJJZ

    Joined:
    Jul 21, 2004
    #3
    I have this... $160 plus drives...

    http://www.cyberguys.com/templates/SearchDetail.asp?productID=12772

    Works great and has a handle! (kinda the reason I bought it:D) I use it when I transport files to and more importantly FROM studios until I can properly back up my content. Site says that it only takes up to 500gig drives but I think it's because that's all that was available when it was released. I think I read on another site a couple months ago that it took 750s as well. With that in mind odds are it takes 1TB drives as well. Swappable drives and trays are a plus. Only downside, only pata drives, personally not a big deal to me. Hope that helps.
     
  4. OCDMacGeek thread starter macrumors 6502a

    OCDMacGeek

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    Jul 19, 2007
    #4
    Although they list prices for buying the hard drives from them in the enclosure, is there any reason we could not supply our own HDs? I might be able to find a better deal on 1 TB disks. (Not sure, but possible.)

    I'm not sure what, if anything, makes this enclosure better than the Venus one suggested by JesterJJZ. Both support Firewire 800. This is assuming, of course, that the Venus really can support 1TB disks.
     
  5. giom macrumors newbie

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    Nov 15, 2007
    #5
  6. ab2650 macrumors 6502a

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    Jun 21, 2007
    #6
    First, you can do it in software, but you lose advantages over having a true hardware RAID, namely performance speed.

    To address some of your concerns, have you investigated other RAID types, namely RAID-5? It is, in short, 'n' drives with one drives worth of parity information, distributed across all the drives. With a dedicated (hardware) RAID controller you get good performance plus data security because you can lose any one drive and still have your data.

    RAID-5 is typically configured in 4 disk setups, so you get 3 drives worth of space, and 1 worth of parity. For 500 GB drives that gives you 1.5TB of storage space and the ability to save your data if any one of those four fail. You could do RAID-5 with less drives or more drives but there is a curve of how much space you gain (over RAID-1) and how safe your data is.

    For instance, if you have 2 drives, you get 1 drives worth of data and 1 of parity; no gain over RAID-1. If you had 16 drives, you get 15 of data and 1 of parity, but now you increased your likelihood of drive failure four times that of a 4 drive configuration.

    The beauty of RAID-5 over 1 is expandability; If your system supports more than two drives you can always start with 2 or 3 drives and upgrade later. RAID-1, even in a 4-drive configuration only gets you more data protection, never more space. (i.e., a RAID-1 array with 4 disks is only as large as your smallest disk, but it can handle 3 simultaneous drive failures)

    Another option is RAID-0+1, a.k.a. "A stripe of mirrors" with 4 drives. Two pairs of drives are striped (data divided equally gives you better performance for read/writing), then you mirror one set to the other (giving you redundancy). In this configuration you can lose 1 or 2 drives and still save your data, so long as the drives you lose are not matched across the mirrors, if that makes sense.

    You're right with all your research, but if you're really considering RAID, I'd go with something more expandable like RAID-5. There are a few NAS devices out there that work beautifully as 4-disk RAID servers, namely the Netgear ReadyNAS and the boxes made by Thecus, but both are fairly pricey. But you may save a little by getting less expensive disks too... You can find a 500gb drive for $99, but a 1TB drive is more than double that... So 2TB in 4 drives would be $400, but in 2 drives quite a bit more.

    Just something to consider.
     
  7. trule macrumors 6502

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    Mar 16, 2007
    #7
    With all the small footprint Linux NAS solutions on the market the best solution for raid is an old computer (1 GHz+), a compact flash reader, Gbe LAN for connection to HS switch (Airport Express etc) and hard disks. If noise and power consumption are a factor then look at the following setup:

    - FreeNAS (boot it of a compact flash)
    - EPIA Mini ITX MB (example Jetway J7F4K1G5 (has raid) or EPIA-SN 10000EG)
    - 2 disk case with heat pipes for CPU (Serener GD-L01)

    That will be a very flexible solution! And much more capable than any low end NAS box! Depending on the case it might even be cheaper.

    Also, forget about the difference between software and hardware raid, at the low end there is none and even if there was a difference it would be hard to notice because the disk speeds are much slower than the software running on a modern CPU.

    However, using two separate external disks for any RAID is asking for trouble, any RAID should run of the same power supply & enclosure.

    A more secure option can be a single disk NAS solution with an external disk connected for backups of that disk. FreeNas can do this, as can many other Linux based NAS solutions. Why is this better? It protects your external disk and backup from physical damage or theft. Also you can upgrade the disk MUCH easier; ie. start with a 500GB disk now (its best value) and when it start to fill up buy a 1000G disk which will have fallen in price. Then use the 500G disk for a long term backup at a different location (parents home, bank strong box, work etc).

    A RAID is fine but it ONLY protects you from disk failure, it does not protect against RAID controller defects, water, theft, lightning strikes and accidental deletion. If you're going to run two disks, might as well get maximum benefit from the setup.

    If you can handle 4 hours down time while you recover from a backup then RAID data protection is not really worth the effort.
     
  8. DoFoT9 macrumors P6

    DoFoT9

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    #8
  9. Nuc macrumors 6502a

    Nuc

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  10. ab2650 macrumors 6502a

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    #10
    Nuc, I really liked the design of the Mecury Elite. However it apparently doesn't do RAID-1 (only JBOD, RAID-0, and independent drives - which is pretty cool)

    I don't think it would work for the OP because they're looking for data protection rather than sheer size (at the cost of increased failure chance). I'm considering getting it just because I can have two volumes mounted at once with only 1 case/powersupply/cable. Thats pretty neat in my book, and it looks dang good.
     
  11. FrenchKheldar macrumors member

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    May 1, 2006
    Location:
    Atlanta, GA
    #11
    How superior are these solutions compared to the WD My Book Premium or Pro II? The WD drives got mixed reviews, mostly because of fan noise but we should be able to find a 2x500GB My Book for less than $300. The enclosures introduced earlier look pricier... I don't need performance but if I can avoid the noise... So which setup should be best for me?
     
  12. DoFoT9 macrumors P6

    DoFoT9

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    #12
    personally if i were you id go for the mybook solution.

    you dont want to be fussing about trying to determine which hard drive you need, then find the cheapest price on the harddrive, then find the cheapest but best case for your situation, then after all that try to find where to buy them so that they cost you the least. it would be much easier buying the pre-made one, i.e. mybook or similar.
     
  13. Nuc macrumors 6502a

    Nuc

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    #13
    I have mine set up as RAID-0. However, my brother got the exact same one and we used Disk Utility to mirror the hard drive so that it was Raid-1. I'm starting to wonder if that is not the right thing to do?

    Please inform me if this is not the right way to mirror a drive because I would hate to see one of my brothers hard drive fail and then can't retrieve data from the backup disk.

    Thanks,

    Nuc
     
  14. OCDMacGeek thread starter macrumors 6502a

    OCDMacGeek

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    Jul 19, 2007
    #14
    Thanks everyone for your great tips. I am seriously considering the FreeNAS solution. I have a Sony VAIO desktop that I could possibly use for that purpose (it is definitely fast enough and has plenty of RAM). I could buy several 500 gb drives and set them up as RAID 5.

    My only concern is that I could negate the value of the RAID 5 setup if I don't manage to set it up properly so that I can rebuild a bad drive. I'm not an expert in RAID setups, but I usually manage to muddle by and figure these types of things out after hours of trial and error.

    FreeNAS does not seem to let you format your drives in the Mac filesystem, but it does support AFP. Using FreeNAS, it looks like I would not need to use Airport Express to share the drives -- it would take care of that for me.
     
  15. ab2650 macrumors 6502a

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    #15
    In that case you're doing a combination hardware/software RAID 0+1. Some people are OK with software RAIDs, and some people aren't. It should be acceptable though, but maybe not the preferred method.

    As far as volume safety, you can lose 2 drives (from the 4 drives total) as long as they aren't on different volumes. You probably know this, but think of it this way: with RAID-0 (stripe) if ANY drive fails the entire volume is lost... This is why you rarely see 8 drive volumes with RAID-0; That's 8 times the likelyhood that you'll lose everything.

    With RAID-1 (mirror) you halve your chances of volume loss after a failure. With an 8 drive RAID-1, you have 1/8th (12.5%) likelyhood of volume loss.

    In your case, if you lose any one drive, you'll be able to recover. If you lose the second drive on the same mirror, you can still recover. What you *can't* recover from is losing any drive from the opposing mirror.

    RAID 0+1 uses 4 drives, gives 2 drives of storage, and has fail tolerance of 1.33 drives.*

    You would get more tolerance (1.66 by my calculations) if you went to RAID 1+0 (aka RAID-10) but it would not be possible with the OWC enclosures.
     
  16. Nuc macrumors 6502a

    Nuc

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    TN
    #16
    I'm still a little confused. I have another dual enclosure that is mirrored (Raid-1) that I use to put important stuff on. I use my other drive (Raid-0) for doing video on. I'm not to worried about losing data since I have it on tape and can retrieve it.

    Now the OWC Dual Enclosure that I mentioned (my brothers) is using software Raid-1. If one drive fails I'm assuming the good drive will continue to work and the data can be accessed. Then I can replace the bad drive and rebuild the mirror so that everything is being backed up again, correct?

    I thought I knew what I was doing with the Raid-1 but now I'm having doubts as to how I understand it.

    Thanks for your help!

    Nuc
     
  17. ab2650 macrumors 6502a

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    Jun 21, 2007
    #17
    Now I'm a little confused. For all intents, you have the following (in your use):

    One 2-drive RAID 1 (mirror) enclosure. I'll call this setup one.
    Two 2-drive RAID 0 (stripe) enclosures (configured in a RAID 1 software array). I'll call this setup two.

    If that is the case, setup one can sustain either drive going down. Simple.

    Setup two can sustain either side going down. Since the individual volumes are stripes, there is a double chance of failure (thats the problem with stripes). The good news is if one drive in a stripe dies, who cares if the other drive goes too... So to summarize:

    If any one drive fails, you're safe.
    If two drives on the same enclosure fail, you're safe (i.e., someone drops the enclosure).
    If one drive for each enclosure fail, simultaneously, you've lost all your data.
     
  18. trule macrumors 6502

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    Mar 16, 2007
    #18
    Its a good idea to ask yourself what you really need and want.

    RAID systems typically only make sense in a server environment where disk failure would result in loss of critical data or downtime. Think along the lines of payment system databases, thats critical. RAID 0 makes sense where high throughput is required, like video editing, or for overclockers who want fast disk.

    Do you need 100% protection against data loss or downtime? If so then RAID 1 or RAID 5 is the solution. Forget RAID 01,10,0+1 as these are very specific solutions used in high transaction databases.


    Most domestic users do not need a RAID solution of any kind. The same number of disks deployed as a backup solution where one disk is used day to day and the other disk is used for routine backups is a much more suitable solution.

    It is also safer as RAID only protects against disk failure, there are many other things that can go wrong with your data.


    I know that many vendors offer RAID solutions, this is because most solutions are based on a Linux kernel that has support for software RAID. They enable it as a feature differentiator so that they can create low and high end products which have different price points and in the case of the RAID systems much better profits. Performance is nothing special as these are not true hardware solutions.


    Bottom line, if you don't know what RAID is then you probably don't need it. There can be many academic discussions about RAID here but in the home environment RAID does not offer very much for the complexity it brings. When a RAID 1 disk fails and you need to find a replacement you will understand what I mean, companies with 1000's of disks do not have these issues.


    A simple FreeNAS setup with a single disk (or NAS disk from company xyz) and an external disk for daily or weekly or even monthy backups + time machine should be more than enough for most home users wanting a network attached disk storage.
     
  19. trule macrumors 6502

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    Mar 16, 2007
    #19
    In theory you would only have to replace the defective disk, perhaps with one of the same model/size. RTM etc.

    There is a pretty good chance you would stuff that up and loose all your data...so keep a regular backup as well!
     
  20. shecky Guest

    shecky

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    #20
    i have a homebuilt FreeNAS box with 4 x 500GB Seagate SATA 7200.10 drives in RAID5, plus an old 40GB IDE drive i use as a boot disk. it gives me 1.2TB of formatted storage and i have it on my network to 2 macs via gigabit ethernet and it works fast and good, usually faster transfer rates than my FW400 drive actually. everything is via AFP.
     
  21. ab2650 macrumors 6502a

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    Jun 21, 2007
    #21
    me likey FreeNas; I would probably go with that if I didn't find a good deal on the ReadyNAS. It sure would be nice to have the box more configurable (like FreeNAS).
     
  22. craig1410 macrumors 6502a

    craig1410

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    #22
    Actually, RAID-1 is even better than that!
    If you have, lets say, a 1 in 50 probability of losing a drive within a year, with a 2 drive RAID-1 array the probability of losing both would be 1 in 2500. For an 8 drive array it would be something like 1 in 39,062,500,000,000. Of course, these figures assume that you replace and rebuild any failed drives as soon as possible otherwise your probabilities fall back by a factor of 50 for each drive which has failed.

    With RAID-0 you are correct though, each drive increases the chance of volume loss linearly so 8 drives in RAID-0 would have an 8 in 50 probability (16%) chance of failure within a year assuming each drive had a 2% chance as before.

    Cheers,
    Craig.
     

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