Help deciding RAID5 v RAID1 - archival purposes

Discussion in 'Mac Pro' started by DoFoT9, Nov 3, 2009.

  1. DoFoT9 macrumors P6

    DoFoT9

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    #1
    hey all,

    I just need a bit of help deciding between a software RAID5 vs software RAID1 array for archival purposes. the RAID will be installed into my hackintosh and shared over the network for TimeMachine backups as well as extra backups from my multitudes of external HDDs.

    i am thinking 3x1TB WD Greens (RAID5) for $103Aus each, or 2x1TB WD Greens (RAID1). my main concern is data loss and speed of the drives. most setups will clearly equal 2TB of total data storage, we feel that will be enough for a few years (will be backing up 2x laptops + 2x iMacs + the hackintosh).

    which one will be faster? (i guess this wont matter as the network will be the bottlebeck) which one will be more secure in the end? (our house tends to have power dropouts). the network is a gigabit network over cat5e, we may upgrade to cat6e in the future if the speed benefits are THAT great.

    i am forced to go with a software RAID via OSX at this point in time because a RAID card is just too costly.

    my current motherboard in the hackintosh is a GA-EG31M-S2 Gigabyte. it has 4 SATA ports and no RAID support - will OSX still be able to do a software RAID? i am presuming that it can.

    anyway, what are the main pros and cons for this sort of setup?

    thanks to all contributors in advance :D

    DoFoT9

    p.s. sorry if this is in the wrong section.. i didnt know where else to put it!
     
  2. nanofrog macrumors G4

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    #2
    1. DO NOT attempt a parity based array (types 5 & 6) via a software implementation. It doesn't have a solution to the write hole issue, and you'd be playing with fire as the saying goes. :eek:

    2. OS X can't do RAID5 anyway. 0/1/10 or JBOD is all it's capable of doing.

    3. OS X should be able to use the on-board ports though.

    So if possible, get a 4th drive, and do a 10 configuration (would suffice as a primary location, not just backup). No parity, and it's capable of better redundancy than a type 5. Given your usage, it's also fast enough, especially if you keep the capacity at 50% or less.

    But as you only want to use it for backups (presuming only for this purpose), JBOD would be a possibility as well, as the drives shouldn't be accessed that often. You get all the capacity, but the speed is that of a single drive (a.k.a concatenation)

    BTW, there are somewhat inexpensive proper RAID cards. The ARC-1210 goes for ~$290USD here in the states. Not sure what it would go for locally though, given the additional taxes,... you guys get hit with in Aussie land. :D :p It would make more sense for a primary logical drive though for your usage IMO (from past posts & emails).

    Maybe take a look at eBay or some other site.
     
  3. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #3
    hmm ok. damn.

    the consumer version cant, apparently server version can. i might be willing to install server version of OSX in order to gain RAID5 - but if there are problems then i dont want to risk it.

    got 3 spare SATA ports on the board, so i dont see a problem implementing software RAID.

    hmm. eventually the drive would fill up. the question is, would the speed of the drive go below the throughput of the network (i.e. below about 80mbps). a RAID10 with 4x1TB drives would give a total of 2TB space correct? extra money for nothing more

    the main purpose of the drive is to backup computers, store backups of movies etc and not really for editing HD movies and all that lol. speed isnt CRUCIAL but would be nice.

    what are the chances of one drive failing? i dont think im very comfortable with having no data redundancy.

    HAHA $290US is not inexpensive :p i was thinking more <$80US. i shall check the ebays

    EDIT: ha! what about this hunk of junk! http://cgi.ebay.com.au/4-Port-Internal-SATA-Serial-PCI-RAID-Controller-Card_W0QQitemZ150385337935QQcmdZViewItemQQptZAU_Components?hash=item2303aa264f#ht_500wt_1071
     
  4. sammich macrumors 601

    sammich

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    #4
    You do not need hardware RAID cards. One of the big sites (engadget or whatever) did a speed test with 16 X-25E's via software RAID on Vista (they got a peak speed of 2.3GB/s). You should be fine. What RAID cards may offer is some cache in case something crashes to finishing writing data to the drive.

    For a simple home solution you should just stick with what works: just do RAID 1, get pairs of drives and mirror them. It's simple, it works and the chances of both drives dying are zero.

    I really wouldn't be worried about speed if it's a backup drive. You aren't accessing data off these drives directly, but accessing the sources of the backups. Speeds won't really ever reach (I'm assuming you mean 80 MB/s), but really, it's a backup, you worry about speed in a backup.
     
  5. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #5
    yup good point. my hackintosh is pretty safe though so i think it might be fine in this case.

    i think i may aswell just do a RAID1. it ends up cheaper then the RAID5 and seems much better.
    however:
    it would be used as a Time Machine backup, about every month or so. it would more be used as a general storage solution for my junk.

    yup sorry, 80MBs as the rest of the house cant really read/write faster then that as they are just laptop/desktop consumer drives - the gigabit ethernet cat5e wont go faster then that anyway i imagine (once you consider overheads).
     
  6. sammich macrumors 601

    sammich

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    #6
    What you're asking for is a redundant backup. A backup that has a backup is rather wasteful (redundant :p). So my very simple solution now is: just have some drives attached to some computer that you either: manually mirror data (drag and drop, or use superduper to copy only stuff that's new), or use TM to backup the various computers. My rather useless/cobbled together system is just a set of 3 WD MyBook's (MediaBackup:1TB, Media:1TB, TM: 500GB) so my backups are arranged manually. If any one of those drives fail, you can see I still have all my data intact, without RAID. And much simpler.

    Caveat: Time Machine backups have come to contain some data that is unique (ie deleted things in the 'past'), so losing the TM drive now involves actually losing stuff you only had a single copy of. Whereas normal backups are mirror images of a drive.

    What say you?

    Got some general idea of what I'm saying from here: http://storagemojo.com/2007/05/30/home-raid-vs-backup/


    (sorry if that above is a mess. None of those sentences were typed out in order lol)
     
  7. nanofrog macrumors G4

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    #7
    What?

    I know the OS X page is confusing (gave me the impression it's only available with a RAID card), but it's been there in past versions, and from posts here on MR, is still in SL's Client Edition. You'll find it in Disk Utility.

    It will depend on the array you want to implement. You can do 0/1/JBOD with 3 ports. Type 5 if supported by the software, but again, NOT recommended.

    You could use a SATA card if you need more ports, and use it's drivers to implement the software RAID. ;) It's the least expensive way to go, especially if you don't go crazy with it. And you won't have to worry about the EFI firmware support. Any BIOS based card will boot, but you will need OS X drivers for the card (or RAID card if you end up going that route).

    No, the speed wouldn't drop. Most green drives are able to pull ~77MB/s reads. So a type 10 would do 2x that, = 154MB/s. Even on the inner tracks, you should still be OK. Assuming you meant 80Mb/s (10MB/s), then it's well above that. 80MB/s, and you could have a problem hitting full speed. I figured on full 100Mb/s Ethernet, which is 12.5MB/s (below what a single drive can provide).

    With 10, it's benefit is improved redundancy over type 5. It can lose 2x drives and still run, as type 5 is only capable of losing 1 drive while continuing to operate (you want to fix it during this time, or your data will end up gone). It's a trade off for the capacity.

    But as it's a backup, you don't need to run this level on a home computer. You can always archive to an online source if you're paranoid (offsite being a better way to cover you from "Acts of God", such as flood, fire,...).

    The same as any single drive of that make/model, given the usage. Where this isn't so bad, is the drives won't be on most of the time (power management settings will shut them off, until accessed).

    Just get a SATA card. As mentioned, you don't have to worry about the EFI firmware boot capability, as it's a hackintosh. You do need to get drivers for it though. ;)

    PCIe or PCI (133MB/s), but it's fast enough for backup. The PCIe cards would be more expensive I think, but worth checking. Say a 4x lane card (typically has 4 ports). They're faster, and would allow you to change it to a primary location down the road if you want. Depends on your plans.

    No idea, as it doesn't say it has driveres for anything, let alone the chip it uses (i.e. Silicon Image provides OS X drivers you can get off thier site). Personally, I'd skip this one. :eek: :p

    sammich, JBOD allows multiple drive to appear as a single logical drive to the OS. ;) Makes life a little easier.
     
  8. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #8
    haha yes, im thinking a redundant backup solution.

    that is a very simple solution. better then my current one though - currently i only backup my computer to our (dead - long story) Time Capsule (which will hopefully be working once the capacitors arrive). i have another 2xtb + 2x500GB HDDs that are not backed up at all. nothing REALLY important on them


    thanks for the link. actually now that i think about it, i just found a PSU (from an old LaCie HDD) that i think will fit into my dual bay FW enclosure. it is JBOD and mirror capable. this would be a secure hardware RAID i take it.

    the question is, mirrored or concatenated. :confused:


    haha that made me laugh. thats aussie talk for you. not organised!




    the wiki page says OSX supports RAID5 software RAID. i guess its only with the appropriate computer/configuration though.

    what is the differences between RAID0 and JBOD? they both appear as one logical drive do they not?
    EDIT: ahh i see, JBOD still had the read/write rate of one disc, RAID0 combines the read/write speeds. JBOD isnt a recognised RAID setup either. im guessing RAID0 writes data to drive one, then the next to drive two etc - where as JBOD just writes until one drive is full. also, i take it RAID0 capacity = the smallest size of the drive, JBOD combines them all together. i think i got it now haha.

    SATA card, didnt think of that! they are cheap cheap cheap. nice suggestion

    sorry, i meant 80MB/s, we have a gigabit switch and all computers support gigabit ethernet.

    good point. in a RAID10 situation you would be pretty unlucky to loose the two mirrored drives i guess.

    sorry, online isnt a viable solution. 25GB per month doesnt allow for that. (thanks Telstra) :rolleyes:

    right so we are talking years then. thanks for clarifying :)

    drivers may be hard, but then again it may be easy. it might even work OOTB!

    no room for PCIe as the GPU is in there, only got one port :(

    i think i shall skip it then ;)


    ok so after all of this i think there are four basic options i can go for:

    1. use the hackintosh, 2x1TB, mirror the drives. only 1TB space :(
    2. use the hackintosh, 2x1TB, JBOD the drives. 2TB space :)
    3. use external dual bay fw400/fw800/usb enclosure, 2x1TB, mirror the drives. only 1TB space :(
    4. use external dual bay fw400/fw800/usb enclosure, 2x1TB, JBOD. 2TB space :):)

    i think i am leaning towards option 4 a bit. the main reason being power consumption (no computer needed).

    i should mention that IF our Time Capsule gets up and running again that it will be used to backup the computers as well - this makes option 2&4 even more considerable.

    thanks to all for your input!
     
  9. sammich macrumors 601

    sammich

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    #9
    Not sure what you're referring to, if it's the set of external drives I have, I'd rather keep them separate. If any of them fail, then I don't want whatever was split to vanish, and since they are separate USB drives, they aren't all necessarily always connected.

    All the drives I have were bought separately over several months so the process of moving data around to make a JBOD (love that acronym) is deterring me.
     
  10. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #10
    ^^ you would be silly to implement JBOD via USB. i hate USB with a passion.

    but yea, saying JBOD does sound pretty cool :D
     
  11. sammich macrumors 601

    sammich

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    #11
    It's rather the "just a bunch of disks" than the actual acronym that's great. (kinda like how I only recently figured out what FUBAR was)

    Unfortunately my only option is USB (and now I've got no spare power points). Being on a laptop, and being limited in computer expenses, I can only have so much FW based ext drives. I really want to build some sort of headless NAS solution (I think I bookmarked a cheapo hackintosh build).

    From before: all RAID/JBOD appear as a single logical disk to the OS. That's the idea silly :p

    Finally:
    I'd choose option 2/4 if you think like I do and don't want/need a backup of a backup
    Or option 1/3 if you still think that a redundant backup is necessary.

    Back to the same question, just how paranoid are you?
     
  12. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #12
    oh haha. i had to google FUBAR.

    same situation here pretty much but dad seems to have caught on with the idea. so may aswell take advantage of it :)

    i edited what i thought about RAID0/JBOD up above. there are some pretty significant differences though!

    WRT paranoia: im not very paranoid. just trying to consider my options. come on i have ~2TB of data that isnt backed up!!
     
  13. alphaod macrumors Core

    alphaod

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    #13
    The server OS does not provide that added benefit. You still need a hardware card, which can be used in the client version anyways.
     
  14. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #14
    thanks for clarifying. the RAID WIKI said that OSX supported software RADI5. thats why i got confused. :confused:
     
  15. nanofrog macrumors G4

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    #15
    It's slightly more complicated than JBOD (concatenation), but it works if JBOD isn't available. It certainly has it's merrits, including the inclination to separate backups manually for whatever reason (i.e. audio, photos, and video backed up to separate drives).

    I actually do it this way, but I like to keep data segregated. JBOD for large files that can fill more than a single disk, in order to prevent a folder from being cross saved (stored on multiple drives).

    Mirrored will waste space. So a pair of mirrored 1TB drives = 1TB available space. JBOD will give you 2TB (no wasted space). This and the fact it's seen as a single drive, is what makes it attractive. ;)

    That's a mistake. Their RAID card supports a type 5 array, but not OS X. It makes sense IMO, given SW implementations can't deal with the write hole issue at all. You'd need an NVRAM solution, or a different implementation, such as Z-RAID (part of ZFS, which Apple dropped).

    Yes, they're both seen as single drives. A stripe set will use parallelism to increase throughput (stripes data across the members), while JBOD doesn't (performance = single disk).

    Must...watch...pennies... :eek: :D :p

    BTW, the FW enclosure is still software based. ;)

    JBOD is capable of exceeding this, but it depends on the drives (i.e. you'd need to look at 7200rpm drives rather than "green" editions).

    A stripe set would exceed it, but with additional risk. If one goes, ALL data is gone. You can survive if the primary locations are still intact, but if not, you're screwed.

    With JBOD, you only have to deal with the data gone on one drive.

    It's not much of an option for me either, but not due to caps. It's more to do with costs, as I have quite a bit of data (~2.5TB). It's slow for the affordable sites, and additional bandwidth is too expensive. I'd also need to increase the ISP speeds as well, further increasing the bill. :rolleyes:

    Stupid US ISP's dragging their feet for increased bandwidth... :(

    HINT: Research. ;) :p


    So PCI it is. :p

    There's cards out there, and PCI is capable of exceeding 80MB/s (32bit cards = 133MB/s). Check the specs carefully though to make sure there's no other issues.

    1. Skip it.
    2. Possible, or even add a 3rd drive to the board.
    3. Skip it.
    4. Possible.

    5. Use 2 + 4.
    6. Use a PCI SATA card.
    7. Use a PCI SATA card + 2 or 4, even both. :p

    You do have options. ;)
     
  16. sammich macrumors 601

    sammich

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    #16
    Any more questions? I keen on finding out where you're going with this, we're on similar levels of risk of our data being FUBAR'd.

    Have to comment on the RIDICULOUS crap that is Telstra counting uploads. I feel for you man. I torrent a little and have recently uploaded roughly 70GB in the 2 weeks since I got my ADSL2+.
     
  17. nanofrog macrumors G4

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    #17
    The only thing that would really FUBAR your data, is a stripe. It's technically possible, and is still less risk than a primary array (due to shut-down by inactivity in power management features), but not advisable IMO.

    JBOD is fine, as is a mirror. But the mirror is a waste of capacity if you're limited in either budget or drive locations (includes available ports). If not, go for it if you feel justified. Only you know the value of your data. It's just that physical constraints and budgets can't be ignored. :rolleyes: ;)

    BTW, I take it you're in Australia as well?
    25GB caps would suck. They're not ubiquitous here in the US yet, but some ISP's have gone that way. I figure it's on it's way though. :mad: :(
     
  18. alphaod macrumors Core

    alphaod

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    #18
    I'm paying for business internet, so I'm not affected by the ridiculous Comcast invisible cap.
     
  19. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #19
    it looks very attractive, i would rather RAID0 though i feel. it seems more secure. if all goes to plan (Time Capsule gets up and running) i shall implement a RAID0 system.


    ahh, i see. i hate the fact they dropped ZFS. grumble grumble.


    thus why i will opt for RAID0 :)


    we call them "cents" :p

    are you sure? i have this enclosure and i was under the impression it could do it via the hardware (there is a switch to choose on the FW device).


    ahh. this brings up more things to consider then doesnt it. thanks nano :rolleyes:. what happens if i am using say a constant 600GB on the JBOD 2TB, and over the space of 5 years that 600GB is used extensively. will this mean that the first HDD has been hammered, while the 2nd hard drive is basically new? i think i would want them wearing equally... but then again you want the data to be recoverable that is available... hmmmm


    there is no way out im afraid! wish i lived in Japan :p

    if only we didnt rely so much on them... :mad:


    you say that EVERY time! haha

    if the solution i pick in the end can do around 80MB/s then i am happy with that, the network cannot go any faster then that! so why would i want to spend extra money on something i can utilise?


    i am liking the JBOD with 3 drives. option 5,6&7 are too costly though :( as much as i would love to! dont get me wrong!

    heaps more questions, they will come though haha. some of my drives are getting on, 3+ years. so im getting a little bit concerned.

    dont get me started. i will rant for a month straight. our uploads are INCLUDED in our cap. 25GB up and down data. terrible

    alphapod: how much do you pay? we pay $100Aus a month for ADSL2+ 20mb down / 1mb up for 25GB, technically we have no cap - but once we go over 25GB we return to 64kbps (or roughly 8KB/s). lovely.
     
  20. nanofrog macrumors G4

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    #20
    I was thinking more about Frontier, as I'd forgotten about Comcast's residential service. Thanks for the reminder. :eek:

    Mine's through AT&T, and so far, no caps. My issue is bandwidth and cost (less value in the mid-range band packages available than the bottom most option :eek:). IIRC, I can't even get the 6.0Mb/s service due to the distance to the exchange. :rolleyes: I'm in a Class C area though, and is at the bottom of the schedule for updating the infrastructure.
     
  21. DoFoT9 thread starter macrumors P6

    DoFoT9

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    #21
    wow.. you get "classed" ?!?! we dont have that honour. :(

    poor you with not even 6Mb/s :(

    p.s. be back soon everyone, moving to a diff house :D
     
  22. sidewinder macrumors 68020

    sidewinder

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    #22
    RAID 0 for backups? That makes no sense. You don't need the speed and the risk is high even if the RAID array is not your only backup.

    Look up SNAFU.....because that is what you will have.

    S-
     
  23. UltraNEO* macrumors 601

    UltraNEO*

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    #23
    It's odd... Every week we hear people who are thinking of using a RAID for backup, when will people start to learn that RAID isn't a archiving solution? :confused:
     
  24. nanofrog macrumors G4

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    #24
    It's fine if you've a second backup of the same data, and as it's an external, you can store it separately from the system, such as a fire resistant safe (won't help you in floods though :p). It can even work as the only backup system, but I would NOT recommend it. Period. If you do, be aware of the risks.

    Also keep in mind, if you go with a stripe set, and circumvent these settings, your risks go up to that of a primary stripe (platters are always spinning, even if the heads are stationary).

    Agian, I don't recommend it as it's dangerous. You don't want to play "high risk" with your backup strategy. Speed's not that important. You set it, and walk away (just make sure the system's active if it's set on a schedule, which I would recommend as well).

    Again, don't do this. It's like storing data on a loaded shotgun, and throwing it into a fire. :eek: :p

    Yes, I'm sure. There's no mention of an independent processor or cache.


    Yes, the data is stored sequentially (in terms of capacity). Fills A, then B,...

    But if you find yourself in that situation, you can use the other drive for something else until your backup capacity reaches a level where you need to use a larger capacity drive or multiple drives (single disk operation, JBOD,...).

    Speed certainly isn't your primary concern here. Capacity for the lowest cost is.

    The board's SATA ports make for the least expensive solution, but consider your primary capacity needs as well. You may end up needing a SATA card anyway (move the backups to the card, and new drives for primary usage on the board).

    Run a SMART test on each, and see what it comes up with. If the data doesn't make sense, there's online resources available (some tools are easier to understand as well, but it's not hard anyway).

    I presume there's no squeals, grinds,... to cause concern. If so, definitely run the SMART test ASAP, and prepare to replace them immediately (seriously, if this is the case, DO NOT drag your feet or data = vapor).

    As per the 6.0Gb/s, it's not a "classed" system. It's the distance from point A to point B. You're into networking, you should know there's distance requirements. :rolleyes: :p
     
  25. nanofrog macrumors G4

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    #25
    Well, RAID is used to backup primary RAID's (and redundant types are used for the backups as well as the primaries). Other than software scheduling, they're not "connected". ;)

    But it's not the same as the questions that's seen on MR. :D :p
     

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