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  1. #1
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    Mar 2005
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    backplane SATA II ?

    hi, what do i need backplane for ? i mean, what is it ?

    Can i make server without backplane? i thought it is just a connection between my motherboard to my disks, but what do i need it for... i can just connect my HDDs with SATA cable directly.

    right? so why even bother with this, especially that it's worth like 100$ at least

    i'm planning to have 4 HDDs, but 4 cables is still not a big deal i think

  2. #2
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    Correct, you can build a server without an SATA backplane by connecting the SATA and power cables directly to the drives. If you're on a budget, you may prefer to do it that way, however we find that for a high-end server in a datacenter environment, a hotswap backplane is worth the cost.
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  3. #3
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    Apr 2004
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    Quote Originally Posted by juice99
    hi, what do i need backplane for ? i mean, what is it ?

    Can i make server without backplane? i thought it is just a connection between my motherboard to my disks, but what do i need it for... i can just connect my HDDs with SATA cable directly.

    right? so why even bother with this, especially that it's worth like 100$ at least
    A backplane offers hot-swap capability for the drives. In other words, when your drive fails you can pull it out and put another one in without powering the server off and have the RAID controller rebuild your mirror (RAID1/10) or parity drive (RAID5).

    If you do not have a RAID controller then there's not much use to having a backplane. If you don't care about downtime and want to run without RAID or want to run with software-only RAID then you don't need backplane.

  4. #4
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    Mar 2005
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    thank you.

    i will use RAID 0, it's motherboard RAID solution, so probably software raid. (it is build on popular Asus G965 chipset motherboard)

    One more question, by the way - is there any siginificant difference between built-in motherboard RAID and for example completly software solution from OS, like linux mdadm ? (or anything other)

  5. #5
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    Nov 2002
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    Linux software raid is mature and stable. The linux drivers for motherboard RAID less so. The motherboard "RAID" does very little - most of the work is done by the processor as it would be with s/w RAID. The usual advice is to disable motherboard RAID and use Linux software RAID.

  6. #6
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    Nov 2006
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    The difference is firmware RAID (which is what this is called) is less stable/tested usually than the linux md driver. But you're talking about raid0 so you must not care about your data anyway.

  7. #7
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    Quote Originally Posted by flaggg
    The difference is firmware RAID (which is what this is called) is less stable/tested usually than the linux md driver. But you're talking about raid0 so you must not care about your data anyway.
    you are confusing caring about data with caring about downtime.

    good and often backups are much more useful than RAID1, becouse probability of hardware failure is lower than probability of human mistake ( for example deleting some files).

    If i use RAID0 + frequent full backups, i dont see why im risking my data. can you explain it?

    And if you use RAID1 without backups, i can see many reasons how you are risking your data. for example - you dont have any way to recover any accidently deleted file (or maybe hackers broke in? or maybe some software corrupted your data? many many possible situations. And every one of them is disaster for RAID1, and is no problem for BACKUP solution)

    but this is just my personal opinion, backups are more important than RAID1.

    of course, in ideal world, you use triple backups every day, on 3 different machines, triple RAID1 with own power generator that can last for 1 month, and so on..

    but in reality (my reality) i need to use budget/mid solutions that are fairly safe. RAID0 (performance leader and lot of space saved) + often backups (at night, whent there is no load, with high compression to save ever more space) are the cheapest and most efficient way, and are also safe - hacker deleted files? no problem, i have backup. software corruption - still no problem. human mistake? same.

    If you use cheapest possible disk, them maybe yes, but paying like 10%-15% more for HDD can give you much more safety. Also, using disks for more than 4-5 years on heavy load machine is asking for trouble anyways.

    do you disagree?

    P.S. for backups you can use blu-ray or hd dvd, or if not, some slow huge disks, that you can not use in RAID1, becouse it will significancy lower your performance.
    Last edited by juice99; 12-19-2006 at 10:48 PM.

  8. #8
    Join Date
    Oct 2001
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    Quote Originally Posted by juice99
    good and often backups are much more useful than RAID1, becouse probability of hardware failure is lower than probability of human mistake ( for example deleting some files).
    Harddrives will always fail - not a matter of if, but when.

    RAID has saved us countless times from the hours it would take to rebuild a server from backups - simply replacing a drive with no downtime is well worth the extra cost.

    RAID1 + offsite backups is an excellent strategy.
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  9. #9
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    one more thing - is there any way to grow software RAID 0 ? assuming my filesystem is supporting this. (and it is, it's XFS)

    i mean, to add one more HDD after some time of working already made array and remake it so it will be included...

  10. #10
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    Oct 2001
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    Quote Originally Posted by juice99
    one more thing - is there any way to grow software RAID 0 ? assuming my filesystem is supporting this. (and it is, it's XFS)

    i mean, to add one more HDD after some time of working already made array and remake it so it will be included...
    There are raid cards that support releveling and resizing arrays while the system is up (you have to umount & sync the drive in Linux to recognize the changes) - 3ware.com has documentation for their cards which contain this information.

    Reminder - If you're growing an array, you'll need a controller that supports more than 2 drives - consider the 3ware 9550SX series
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  11. #11
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    is there a way to grow software raid 0?

  12. #12
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    Nov 2006
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    College Station, TX
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    Quote Originally Posted by juice99
    is there a way to grow software raid 0?
    MaB answered that. The answer was: You need a 3ware card that supports it specifically, and you'll still have some downtime while you unmount and remount the drive.

    Linux software raid will not support it. (In theory you could repartition using qtparted from a boot CD, but ... uh, don't ask ME to test it with a server in a production environment.)


  13. #14
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    Nov 2002
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    Quote Originally Posted by karlkatzke
    MaB answered that. The answer was: You need a 3ware card that supports it specifically
    The poster was asking about software RAID. 3ware is hardware RAID.

    I don't know whether it's possible to grow the actual RAID volumes. Probably not. Linux's logical volume manager can be used to make logical volumes that span multiple physical volumes, so you can probably achieve what you want using that.
    Last edited by garrence; 12-23-2006 at 09:47 AM.

  14. #15
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    but in reality (my reality) i need to use budget/mid solutions that are fairly safe. RAID0 (performance leader and lot of space saved) + often backups (at night, whent there is no load, with high compression to save ever more space)
    I wouldn't consider that safe at all. You must think about how much data you'd lose when a drive failed. In your case, you oculd lose a whole day's data. I run customer's shops I don't think they'd like it if they lost a whole day's orders...

    I think you're nightly backups are a good plan, and take them off site regularly (rsync them to your home PC will do), but with RAID0 you are increasing your risk of data loss considerably as if either of them die, everything is gone. If you had 2 drives and put /home on one, and the OS on the other you'd be safer, but not nearly as much as RAID1 or RAID5 would be.

    Think how long it will take to restore your backups, that should factor in your plans here.
    Do not meddle in the affairs of Dragons, for you are crunchy and taste good.

  15. #16
    Raid0 with 2 hd's is doubling your chance of a hardware failure. If they are new drives, I'd make sure they get a good month or two of use before becoming production servers because if they are going to fail they will do it right at the begining or right at the end :-)

    Raid1 - don't remember the numbers exactly but it takes the odds of catastrophic failure from once in 3 years to once in 20 years (or something along those lines).

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