Data Backup(RAID): Build new system or Raid card

Discussion in 'OT Technology' started by mystix, Jul 2, 2008.

  1. mystix

    mystix OT Supporter

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    Ok, itunes fucked up my music again. I have backed up all my music but all my ratings and etc are gone. So I am done with the nvidia raid that I have previously used. So I have two options. I'll be reusing my 2 320gb hd

    Build a seperate system, run windows server or linux and run RAID1

    found someone selling
    P4 630 Prescott 3.0GHz 2MB L2 Cache with Asus P5LD2 motherboard
    for $80bucks
    Add some ram and i'll be set.

    or

    Adaptec SATA RAID controller, model AAR-2410SA for $100
    add it to my existing system

    I have no clue how controllers work, but everyone raves about hardware raid.

    So OT, whats my best choice?
     
  2. deusexaethera

    deusexaethera OT Supporter

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    Wait, why are you blaming the RAID? You said iTunes fried your music collection.
     
  3. dorkultra

    dorkultra OT's resident crohns dude OT Supporter

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    raid 1 should not be used as a backup
     
  4. lowfat

    lowfat 24/Mac/SciFi/PC Crew OT Supporter

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    :hsugh: on a separate computer, why the hell not?

    Hardware RAID for RAID1 isn't going to be a huge difference. A little bit of performance, but not a great deal. Hardware RAID controllers help substantially when there is parity involved.
     
  5. s2k

    s2k OT Supporter

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    why?
     
  6. P07r0457

    P07r0457 New Member

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    RAID1 does not have parity :ugh: So I'm not sure why you're talking about the benefits of discrete raid controllers when parity is involved -- because that isn't remotely relevant to raid level 1.


    Personally, if you KNOW you'll never want more than 320gb, then just build a file server, and use a discrete card and a level 1 raid. BUT make SURE you use a decent DISCRETE controller. onboard == fail and aids, unless you're talking higher-end server mobos.

    However, if it were *ME*, I would get some extra drives, and run RAID5.
     
  7. dorkultra

    dorkultra OT's resident crohns dude OT Supporter

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    on a separate computer raid 1 is fine. on the primary computer with a raid card, you should always have a separate backup
     
  8. lowfat

    lowfat 24/Mac/SciFi/PC Crew OT Supporter

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    I never said RAID1 had parity, I said hardware controllers help substantially when parity is involved, not that RAID1 had anything to do with it. He asked if a hardware raid controller would be beneficial to him, I have him an answer :hsugh:
     
  9. P07r0457

    P07r0457 New Member

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    okay well i think it would have been prudent to specify that you felt that raid5 and an extra hard drive would be benefitital to take advantage of that parity.
     
  10. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    I don't get your hate for onboard RAID 1 solutions - I'm not sure how it can fail so badly that you would have one working drive wors case scenario.
     
  11. P07r0457

    P07r0457 New Member

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    the drive failing isn't the big downfall of onboard raid solutions -- it's the controller failing.
     
  12. piratepenguin

    piratepenguin New Member

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    vhat?
    parity = protection against one disk failing or am i wrong?
    in raid 1 one data is mirrored against all the drives .. therefore any amount of drives can fail except 1, and you still have all your shit?

    im wrong?
     
  13. P07r0457

    P07r0457 New Member

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    yes you're wrong. what you describe is redundancy. parity is one method for acheiving that redundancy.

    so parity implies redundance, but redundance does not imply parity.
     
  14. piratepenguin

    piratepenguin New Member

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    ok, what is parity?

    ensuring all the data is on at least 1 drive?
     
  15. P07r0457

    P07r0457 New Member

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  16. piratepenguin

    piratepenguin New Member

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    also, for a raid 1 (for my OSes) what's wrong with software raid? is it fail and aids? or is it simply slower? by a lot?
    how much would a cheap and reliable controller cost?
    even if im already doing a raid 5 - I should have 2 raid cards?

    i dont think i will setup a raid 1 because i will prob have 3x500gb drives in a raid 5 that ill fit my oses on, but in the future if i begin to find it tight for space, i might buy 2x100gb SSDs (this could be 5 years down the road) to relieve some space in my raid 5 and also do a lot to improve performace.
     
  17. P07r0457

    P07r0457 New Member

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    dont worry today about something you MIGHT do with your computer in 5 years. that's just stupid.
     
  18. piratepenguin

    piratepenguin New Member

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    im trying to understand raid, i asked a question about software raid

    edit: still dont get how raid 5 does parity and raid 1 doesn't. it seems pretty important so i dont think ill do a raid 1, but how does raid 5 have it and 1 doesnt?
    edit: im slightly getting it
    edit: yes.
     
  19. P07r0457

    P07r0457 New Member

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    raid 1:
    [​IMG]
    A RAID 1 creates an exact copy (or mirror) of a set of data on two or more disks. This is useful when read performance or reliability are more important than data storage capacity. Such an array can only be as big as the smallest member disk. A classic RAID 1 mirrored pair contains two disks (see diagram), which increases reliability geometrically over a single disk. Since each member contains a complete copy of the data, and can be addressed independently, ordinary wear-and-tear reliability is raised by the power of the number of self-contained copies.



    raid 5:
    [​IMG]
    A RAID 5 uses block-level striping with parity data distributed across all member disks. RAID 5 has achieved popularity due to its low cost of redundancy. This can be seen by comparing the number of drives needed to achieve a given capacity. RAID 1 or RAID 0+1, which yield redundancy, give only s/2 storage capacity, where s is the sum of the capacities of n drives used. In RAID 5, the yield is s * (n - 1)/n. Using 1 TB drives as an example, four of them can build a 2 TB redundant array under RAID 1 or RAID 1+0, but they can be used to build a 3 TB array under RAID 5. Although RAID 5 is commonly implemented in a disk controller, some with hardware support for parity calculations (Hardware raid cards) and some using the main system processor (Motherboard based raid controllers), it can also be done at the operating system level using Windows "Dynamic Disks" or with mdadm in Linux. A minimum of 3 disks is required for a complete RAID 5 configuration. In some implementations a degraded RAID 5 disk set can be made (3 disk set of which only 2 are online).

    In the example on the right, a read request for block "A1" would be serviced by disk 0. A simultaneous read request for block B1 would have to wait, but a read request for B2 could be serviced concurrently by disk 1.
     
  20. piratepenguin

    piratepenguin New Member

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    so if there are parity errors reading, then, i guess the data can be retrieved off another disk and hopefully the parity matches, yes?. are errors reported and how?
     
  21. Limp_Brisket

    Limp_Brisket New Member

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    it's good for backup in terms of hard disk redundancy. if itunes fubared his music collection, it would do so on both raid disks. it doesn't make historical backups.

    if you're making yourself a raid for home and you have 2 extra disks, raid-1 is fine. raid-5 requires a 3 hard disk minimum.
     
  22. P07r0457

    P07r0457 New Member

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    depends on the controller. one of the reasons a good controller > onboard.

    parity is used for error checking, as well as to rebuild a data set if a drive fails. errors are generally reported, yes. most controllers have some way of accessing the data. often snmp can help collect data and it can be analyzed with cricket/mrtg or other statistics packages.
     
  23. 5Gen_Prelude

    5Gen_Prelude There might not be an "I" in the word "Team", but

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    Yeah, but what's the big deal if it does? You buy yourself a separate card and rebuild the mirror?
     
  24. deusexaethera

    deusexaethera OT Supporter

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    Okay people, get off the RAID thing. He could be running a server cluster connected to a RAID60 SAN and it wouldn't matter, because what iTunes does to his music collection is its business; the disk, whatever kind it may be, is just going to do what it's told to do.

    But since it's a going concern, I might as well throw in my two cents: RAID1 is fine for backups even if it doesn't have parity, because instead it has a complete second copy of the data. You don't need parity to reconstruct the data in case of disk failure, not when the entire data is redundant.
     
  25. deusexaethera

    deusexaethera OT Supporter

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    The problem is that if the onboard controller fails, what are the chances you're going to find another controller that can detect the existing array and bring it online again without having to wipe the disks?

    I, for one, use a RAID so I don't have to make backups of non-important files, but if the controller fails and I can't just swap in another identical controller and I end up having to wipe the disks and make a totally new array, then there goes my evil plan.

    (I also use it for speed, but that's not the issue here.)
     

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