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Thread: Mac OS X and opensource RAID software?

  1. #1
    Join Date
    Mar 2001
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    Austin, TX, USA
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    Hey,

    I am wondering if we will see something like this available on Mac OS X. I am pretty sure software RAID is built into (or can easily be added) Unix. What would it take to incorporate an opensource Unix CLI based RAID driver?

    Other interesting links:
    Vinum: a FreeBSD software RAID driver. The author is currently looking for a port to OpenBSD and NetBSD)
    Librenix:
    a general software based RAID on Linux site

    [This message has been edited by drbobguy (edited 22 March 2001).]

  2. #2
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    Mar 2001
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    Austin, TX, USA
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    Looks like other people in the mac world are wondering the same thing about BSD RAID. A good how-to on using vinum in BSD.

    So my question is since Vinum uses its own format, if you mount a drive in the command line in OS X, will it appear as a drive in Aqua? Anyway...just some food for thought (I wouldn't want to hurt SoftRAID's business any).

  3. #3
    Join Date
    May 2000
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    wherever I hang my hat
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    hey, you know what? It might be good for them. Competition is always good.

    I'll ask Mark James to surf thru, and see what he thinks.

    great links--thanks for the great post!


  4. #4
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    The Linux RAID stuff we have looked at is not robust enough for serious use, in our engineers opinion. And, the GUI is miserable to pathetic.

    I appreciate the BSD reference, It may have more promise as a robust implmentation. BSD guys are more serious than Linnux guys on stuff like this. I am not knowledgeable about this "product", so do not have info to base any opinion on. It does look like yet another GUI-less interface, though, so it is not going to be very popular even if it were ported to OS X.

    the problem is that we need finished driver kits from Apple.The fact that OS X is based on BSD does not make this kit automatically portable. Apples implementation is very different, so while certain file structures would be useful, it may be easier to write from scratch than to use code like this.

    thanks for the support, all. We expect to have SoftRAID in the summer 2001 for OS X. It will take a few months AFTER we get the final developer driver kits from Apple, and as of today, as far as I know, they have not been released.

    Without them, it is possible to send data to a disk, but not to get error information back, two way communications, etc.

  5. #5
    Join Date
    Mar 2001
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    vinum works relatively well, though NetBSDs RaidFrame has generally worked out better for people I know who do this sort of thing. The major problem I see for implementing a Software RAID Driver on OS X is that IOKit does not encourage it topologically. IOKit likes things to be a tree, drives spread from the controller, partitions spread from drives. RAID pulls subparitions back into partiions. The straightforward (i.e. not so good) way to is to have a Driver that competes with the PartitionMap drivers on published storage objects. Whenever it matches (finds its raid signature) it read some metadata off the partition, then throws it into a global pool have available Raid partitions. Whenever a new driver is added you try to detect a set, and if you do you publish a new Storage object (which somehting else, probably one of the FS Extensions) will match. This works in the tree, because only the dominant link is technically connected (in IOSpeack it is the IOService provider of the effective IOMedia object the the seperate RAID partitions form). The problem with this is that you will end up with one of the subpartitions of the drive being dominant in the IORegistry, which means that while all the other parts can be hotswapped, if the dominant one is removed the entire RAID IOMedia object will collapse. Dynamically handing off the dominance may be possible, but it seems very kludgey to me.


    Louis
    ---------
    Louis Gerbarg
    Darwin Developer

  6. #6
    Join Date
    Jul 2000
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    Walnut Creek,Ca.US
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    Mark: is this true?
    Santilli:

    quote:
    --------------------------------------------------------------------------------
    Meanwhile, the others, read perhaps Adaptec, but more important softraid, can't even start working on drivers for OS X until the developers drivers
    package is finally released.
    --------------------------------------------------------------------------------

    wrong.
    check your facts next time. please. the "driver package" is done, was packaged with dp4, was free with mac os x pb, is free with mac os x, and the api's are open source...and apple engineer's monitor the darwin dev-lists and give *free* help to driver developers among other things.
    the iokit api's needed to implement a pci scsi controller have been available since dp4 or *earlier*.

    iirc, adaptec had beta drivers for some of their cards ready for the pb.

    "

    gs

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